Correct. Most people misunderstand this and think that hardware accelerated drawing is all what they need, but there's another element: decoding. No browsers support (officially) hw-accelerated video decoding on Linux. Compare CPU usage of 4K in-browser video playback on Win and on Linux, the difference is major. On Linux, one CPU core is almost maxed out when playing 4K, on Windows the CPU barely does anything.

You can patch Chromium but no distros ship it like that.

If you'd like I'm happy to provide references to Chromium and Firefox bugtrackers that support the above.

Eg.: https://bugzilla.mozilla.org/show_bug.cgi?id=1210727

https://bugs.chromium.org/p/chromium/issues/detail?id=137247

"Enable VAVDA by default on Linux for VA-API-assisted HW video decode

Currently there are no plans to do this"