I keep trying to give a discount for this, in some sense, but it's hard as time marches on and I've seen some of those deep improvements, while also seeing UX left on the table.

Don't get me wrong, afaict, Firefox will get decent wayland support, new fractional support, vaapi, etc, etc on Linux desktop before Chrome, and for that I can't say Thank You enough. All to say, thank you for this perspective. I wish I knew what to really do about it (I'm not qualified or blessed with the time for C++ contributions).