The funny thing is that this issue never affected Version 16 at any revision, it was actively implemented starting in Version 17. I looked into this back when version 16.2 started issuing this warning, and it has to do with 11_0 vs. 11_1 "feature set" in the video card itself. You can have DX12 installed in Windows, but this has nothing to do with this. Specifically the video card need to support 11_1. I suppose that cards produced after 2015 do support this, but prior cards may not.
Anyway I took the time to compare the last version which didn't complain about this which was v16.1.2, (after this v16.2 came out) and the last of the v16's which was v16.2.5, the last before v17 and using a benchmark test running in a Windows 10 VM, there was no difference in 3D performance. However testing the same in v17 cause an EXTREME slowdown, so instead of getting frame-rates as low as 4 FPS with acceleration, this was reduced by maybe a factor of 10. So to get 3D acceleration in Version 17, you need to obtain a more modern GPU which supports the 11_1 feature set.
I don't know why they did this because they do claim the software supports all versions of DX. It forces people to purchase newer hardware for no real good reason, which adds a lot of waste to the environment unless these items are resold. Why is it not possible to still enable 3D acceleration with older cards, can't be that much "extra code overhead". I'm not a programmer so I don't know, but I think humanity needs to be more careful about waste before we destroy the planet and our quality of life completely by being wasteful.
I'm attaching screenshots of my test results.
2D and 3D performance of v16.1.2
2D and 3D performance of v16.2.5