Really? The No True Scotsman fallacy?
You need to let the vendors that are making EYPC based workstations that they don't know what they are doing. They appear to disagree with you. Might I recommend that you visit Velocity Micro and take a look at the ProMagix™ HD150 Epyc Workstation. See what you could get for the same $6,000.
If you are working 3D, why on earth are you staying with Apple?
1. I can raid 2 NVMe drives in a RAID 0 and have 9Gb thruput. You will have the joy of paying for that performance when you buy yourself an NVMe, but will be unable to use it. Does this matter? It does to me - with digital vendors making texture sets ever larger (512 x 512 to 8,000 x 8000), these damned things are getting to the point that I have to move stuff on and off spinning rust. I can have that today - even on a low end Ryzen based system - the 7,1 will never have it.
2. Google EYPC workstations yourself - there are a number of them from Boxx to Velocity Micro. Velocity Micro makes both TR and EYPC based workstations. (And they will be building me a system in Jan) They even have a dual CPU socket system (HD 360A). I'd point out that for $6,000 (HD150), I'd get 3 times the cores, 4 times the memory, 4 times the hard drive space, and a current (as opposed to obsolescent) video card. Not only will I retire my 4,1, I'll also retire my render farm.
EYPC chips are designed for anybody that needs lots of cores (128cores/256 threads), ram (2TB total) and/or PCIe lanes (128). All of which are more than a 7,1 will ever have.
The Upcoming TR will start at 24 cores, and will take over the HEDT market like the Ryzen has taken over the low end and mainstream market. Low power Ryzen chips are on the horizon for laptops next year.
And one more thing.......
Why do you think Apple is using consumer level video cards for their "workstation" as opposed to their line of workstation cards?