I only use it for those very few sites (less than 1% for sure), but not having it handy at all is just not an option.
As for my mom, luckily she hasn't had any complaints so far, so she just uses Firefox as it's what's installed by default. I certainly don't think I could train her to switch between two different browsers, though. If it came to that it would have to be Chromium full time, there.
One site that deserves a plug here is binance.com. They stopped working with Firefox a couple of months ago, but it was fixed in 2-3 days after I reported it. I guess a little healthy (heh) competition goes a long way.
Just sometimes I'll go 'display: flex; justify-content: center; align-items: center;' and the content will end up about 5px above center. I'll be like 'WTF?' for a minute, then run it in chrome with no issue.