A comment on why to include Win 7 support for the latest graphics cards: Competitive overclocking. For the latest cards - GTX 1080, 1080 ti, 1070, 1070 ti, RTX 2080, RTX 2080ti etc - to be competitive in contests that include older legacy benchmarks, there has to be support for the operating system in which those benchmarks run best.
In a few cases, that even means Windows XP. I'm at a disadvantage since I don't use XP.
In many important cases, that means Windows 7. Examples are 3dMARK Ice Storm, Cloud Gate and Sky Diver benchmarks. There are a handful of others. I get the "full power" of a RTX 2080 ti with z390 mobo with i9 9900K CPU for those benchmarks in Win7.
Certainly in any benchmark using DX12 or RTX features, Windows 10 is required. Firestrike benchmarks are found in the same 3dMARK software package as the above. The Firestrikes don't use any Win10 specific features, but the run best in Win10. There are DX12 and RTX benchmarks in that package, too.