I believe Valve dropped official Windows 7 support in Steam because Chromium did and they weren't going to fork it.

I empathize if you don't like any version of Windows newer than 7 or XP, but it's time to let the dream of running them forever go. It's not weird when software doesn't support the 2009 version of an operating system anymore in 2024. If they never dropped support, it would be difficult to take advantage of improvements that occurred in the last 10 years, because we'd forever be stuck in baggage.

Of course when it's feasible everybody loves software that really never does drop support, like 7-zip, which I think happily still works on Win9x without KernelEx... but I'd rather 7-zip stopped having serious security issues than continued to work on old Windows versions.