> Why bother using FF at this point? Most sites don't work as well, and Mozilla seems actively hostile to my use case.

I share some of your gripes and I do think that Mozilla routinely drops the ball with Firefox, but that's a gross overstatement. I exclusively use Firefox as my main browser (both on desktop and mobile) and I only very occasionally stumble upon websites that will only work correctly on Chromium.

It's annoying when it happens but it's most definitely not "most sites" in my experience, it's a small minority.