I've decided to jump back into this thread in a genuine bid to try to understand your point(s) and share my point(s) as simply and clearly as possible. This attempt may go nowhere, but I truly hope I can get to the bottom of what you're trying to say, without any personal criticisms. Just your point(s) on their merits alone and my point(s) on their merits alone.
I'll leave my source material for your comments just to this thread. Please feel free to clarify on your point(s).
1) You say that "no serious soundtrack composer would use a laptop as his master machine"
My response: That's your opinion. I disagree. There are plenty of "serious" soundtrack composers who would or could use a laptop as their master machine if they wanted to. But more to the point and in a larger context, a modern high-end laptop -- for example, a high-end DAW laptop from the likes of ADK (I own one and can vouch for them) and a high end laptop from Apple (I also own one) are both more than capable of being a primary front-end for a "serious" soundtrack composer, not to mention for many other pro audio purposes, such as post production, sound design, mixing, mastering, composing in general, and any number of other pro audio applications. And I should add that not everyone in this forum or who uses Cubase in general is interested in being a soundtrack composer -- there are plenty of people here that are pros or have pro aspirations who do plenty of professional work on laptops and on computers far less powerful than current-gen high-end laptops.
2) You say, "Logic Pro is the only valid reason to use a mac, for anyone who just starts."
My response: This is simply incorrect. Logic Pro is of course not the "only valid reason" to use a mac, not to mention macs are not just "for anyone who just starts." Not sure where to begin on that one. But I'll simply start with this fact: a major "valid" reason why people choose one platform or another is simply personal preference. Some people simply prefer to use a Mac, some people simply prefer to use Windows, and there is nothing wrong with that either way. That is one of my main points of prior posts in this and other threads.
Additionally, a recent-gen Mac with a quad-core CPU or better is perfectly capable of running professional audio applications and generating professional results. It's suited for many levels of music production task, from beginner to seasoned pro, in any genre and professional submarket of the music and audio industry. Likewise, you can easily find Windows computers that are also suited for the same tasks. Either platform is capable of any number of pro audio, amateur audio, and beginner audio tasks.
Beyond personal preference and capacity to handle most any type of pro audio task, there are many other "valid" reasons why one person might choose one platform or the other:
a) easier compatibility with friends, collaborators or clients
b) TCO - total cost of ownership (this can be complex calculation that goes far beyond a single computer)
c) business requirements
d) contractual reasons
e) support contracts
f) familiarity of specific hardware/software
g) requirement to use a specific piece of hardware or software
h) client preferences or even client requirements
j) pre-existing software/hardware infrastructure investment
k) project workflow
l) performance of a specific application or plugin
3) You say that a "macbook is a consumer-grade machine that would never ever pass military standard testing, like most business laptops do."
My response: Assuming you are referring to a MacBook Pro, not an old MacBook, your point is irrelevant. Military testing is not required, and in fact "most" business laptops are in fact NOT military tested. Some are, but definitely not "most." In any case, a current-gen MacBook Pro is more than capable of producing professional results, and, speaking from experience of owning many business laptops, the current MacBook Pros are built very well, and perfectly capable of handling the rigors of day-in day-out professional use. "Military standard testing" is of course not required. There are also plenty of Windows machines that do not have "military standard testing" that are also perfectly well suited for professional music production. I can personally vouch for ADK computers, for example, which are NOT military tested the last time I checked, and they are some of the best pro audio Windows laptops in the industry. And I can also personally verify that while very well built, the ADK laptops are not as well built or as well designed as my MacBook Pro. However, in either case, I'd be happy to use either machine for professional audio work.
4) You say that "There's nothing you can do to improve a mac....You cannot tweak a mac because Apple won't let you."
My response: That is incorrect. There are plenty of things you can do to both improve and tweak a mac, and also customize and configure them in many ways, besides the obvious hardware and software additions. Of course, you can tweak and customize Windows computers far more than Macs, since you have easy access to the BIOS of PC motherboards, but your statement is very misleading. OSX is a modern POSIX-compliant operating system built on Unix, as I'm sure you know, and there are numerous under-the-hood tweaks you can make to services and features running on Macs that are not that different than changes you can make to Windows machines. In fact, if you have a strong Unix/Linux background, there are plenty of things you can do on OSX under the hood that are very fascinating indeed. But even on a simple level, there are several minor tweaks I use on my Macs that are helpful for DAW use, from disabling Spotlight, disabling FileVault, changing the power profile, hiding alternate boot volumes with fstab, etc. Those types of tweaks are actually similar in principle to simple tweaks I also do to my Windows machines. But beyond that, there is a whole community of Mac Pro users who have been using different EFI firmware on their Mac Pros, for example, so they can upgrade their CPUs to a newer generation of CPUs, etc. I've personally tested this, and was able to increase memory speed and CPU support. There is a community of users who have modified graphics firmware, motherboard firmware, tweaked drivers extensively, not to mention an entire community of people who support Hackintoshes so you can run OSX on an even wider variety of custom hardware if you want to. And on top of all that, Macs run Windows very well via Boot Camp or Parallels Desktop, etc. The number of things you can actually do to a Mac and with OSX in general is pretty impressive. Multi-booting on a Mac with Windows, OSX and Linux is quite easy to do, which opens up other interesting doors as well.
5) You say, "plugin count isn't everything (granted, it depends on how you work...)"
My response: agreed. :)
6) You say, speaking of James Horner, Trevor Rabin and James Newton Howard using Macs, that "They use mac because they're old and not very tech-savvy and they can't get accustomed to another OS."
My response: I can't speak for James Horner, Trevor Rabin and James Newton Howard, but I think you can't speak for them either. Maybe they are old. Maybe they are not very tech-savvy. Maybe they can't get accustomed to another OS. Maybe not. Maybe they just like using Macs? In any case, they are professionals using Macs and doing fine, which simply supports the fact that there are plenty of pros of a high order that use Macs for this specific class of work... not to mention there are many other pro audio tasks done on both Macs and Windows that have nothing to do with film scoring. The post production industry in the US is dominated by Pro Tools, mostly running on Macs, in my experience, as I am sure you know. We could talk for hours about various sub segments of various entertainment industry professionals that use Macs in large majority to Windows. In any case, the platform is irrelevant to the level of work produced. Users of both platforms are limited only by their own skills and talents.
My general position is that the platform wars are over. It's no longer relevant what platform you are running on, other than mainly workflow and personal/business preferences. Whatever works best for you and your unique situation. Performance is of course better on Windows -- as I have stated before, you will of course get more bang for the buck on Windows. I have never argued otherwise. But the delta between Windows and Mac performance is smaller than ever, based on tests I have run myself, having been a heavy Windows user and follower of TAFKAT's excellent DAW Bench work. While there is no doubt a Windows machine of the same price as an Apple machine will give you more plugins and better lower latency performance, the difference in price, amortized over the total cost of ownership in a business lifecycle is not that much, so it is not the headline issue it once was. There is no need to battle it out with Mac vs Windows, in my view. The two platforms can and do co-exist perfectly happily in the same studios where professional work is being done and paid for. And thank heavens for VE Pro, which makes working with both platforms better than ever.