Why would thunderbolt be a problem (Outside of the fact that it is still a solution in search of a problem.)?  TB is available on AMD boards today.
I consider a high end machine one that has a lot of cores, a lot of ram, and the ability to add anything to it I need.  (I do 3d art)  That isn't a Mac Pro.   A low-end Threadripper system will outperform a maxed out 7,1.  IPC matters, the ability to use GPU computing matters.
Threadripper systems are high-end systems.  Eypc systems are high-end systems (Yes, you can get Eypc based workstations).
A 7,1 starts at 8 cores/16 threads - $1500 worth of parts in a $4,500 enclosure.  A $2,500 Ryzen system will out perform it.  A maxed out 7,1 ($54,000) is outperformed by a $10,000 Threadripper or Eypc workstation.  Every subsystem in the 7,1 was obsolete the day it launched.  The CPU, the GPU, the i/o, the storage.  It would have been a good, albeit overpriced system in 2016.  Furthermore, Zen 3 based CPUs are drop in replacements in AM4 boards, TR40 boards, and Eypc boards.  If your hardware is nothing more than a dongle for your software, that isn't a big deal. 
In 2020, a 7,1 is yesterday's tech at tomorrow's prices - that is Tim Cook's Apple.  The days of being on cutting edge tech ended when P.T. Barnum handed the reins over to Timmy.