Because that is IMHO the most relevant point (for me), the performance is there, just don’t expect that kind of performance at low latency buffers (on the 3900x)
I’m not arguing that the 3000 series are bad, or that they are not priced better.
I actually agree with what You are saying, I was just a little disappointed that the two chiplet design of the 3900x still has a negative performance impact.
Although after looking over the charts again, and looking at what buffersize I realistically could use, (RME Raydat PCIe. 128 would be low enough for anything I do), I really need to lighten up 
Now the only “relevant” question is: Will Cubase be able to keep up with the ever increasing core count, that is going to come over the next years ?