I always had all the codecs and Vaapi on Firefox worked fine, but could specifically never get Youtube on Chromium to use GPU decoding, that was the main problem you're reminding me.
In this past year, I've since moved to Windows after like 7 years of constantly messing and tweaking Linux to kinda sorta almost for some stretch of time get all the things to work after spending hours looking for the right configuration. Look at how long this thread is, for example[0]. Or here most saying it still doesn't work[1] and the flags constantly change. Before Linux I was about 6 yrs on Mac. I hadn't used Windows for so long, it actually felt weird to have so much hardware and software support for anything I ever need to use.
I'll take your word for it that Chromium sometimes uses hardware decoding now. But as you say, and they should put that slogan on a T-shirt: "Linux on Desktop: not officially supported and it has broken a lot over the past due to lack of support and quality of driver". I wouldn't really characterize that as "have no problem using". It feels nice to have a system that just works without all that hassle and tweaking so I can just get actual work done, or watch Youtube efficiently without brittle configuration, no window manager bugs etc.
[0] https://bbs.archlinux.org/viewtopic.php?id=244031&p=40
[1] https://www.reddit.com/r/linux/comments/1ey4n2k/heres_how_to...