Nothing sarcastic in my reply, but I will indulge your rant ;- ). This is not economic grievances thread, that would be one section above (General CG discussion).
3960X will come just slightly bit more than 3950X + 1920X. Unless you absolutely need second machine (but you already have those Xeon builds). It's not just about "cores". 3960X is faster than 3950X + 1920X, there has been two generations since the one. 16 core of 1st gen ZEN, is almost the same as 8 cores of 3rd Gen ZEN2.
But it's going to be much more useful to you because of:
1) expansibility (having only to increase memory on one PC, not two, and memory will get lot more expensive soon). What if you'll need 32GB ram? With 3960X you will only buy 32GB, with 3950X + 1920X you will need 2x32GB,etc.
Anything you might save right now, you will lose over the longer period of following years.
2) useful performance - Faster Interactive, is far more useful to productivity than comparatively slow Distributed rendering.
3) resell value. The 1920X is not something you will be able to sell even year from now. I can't even sell any of my 2990WX, no one wants them.
If you don't have the budget for more than 3950X, than buy only 3950X, but don't buy second 1st gen Ryzen just because. It doesn't make economic sense, which you allude being the most important factor.