Dorico and Cubase have a very different purpose, so it’s barely a surprise that one is better in one area than the other. Cubase is for recording and producing audio (with a simple score editor as addition) while Dorico’s objective is music engraving for printed sheet music (or screen, as of late), with a simple playback mode for VST instruments. It’s usually not feasible to create an all-in-one software because that becomes bloated and users just don’t usually have the need for such a universal software because they are working in their own niche themselves. Also, the more complex a software becomes, the less user friendly it becomes. You can’t have both. And from a developer’s point of view, if you’re trying to please everyone, eventually you’re not pleasing anyone.
Also if a “send to Dorico” or “send to Cubase” was that simple, I’m sure the developers would have done that already.
And I’d be curious to see the competition that displays the integration you are referring to.