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.