Chrome has the special sauce — distributors and administrators cannot rebuild it, only Chromium.

Flip the flag then.

It's crazy to suggest they should give web access (not just webgl, but CSS styling) to a buggy GPU driver by default without an opt in by the user.

Is that different than the branding/trademark issue that Firefox also had for years?

(Not bring cynical, I genuinely don't know.)

Yes, it's different. You can build trademark Firefox so long as you do not modify it at all. You cannot build Chrome from the chromium sources — there are components which are not present in the open source repository. It's not just the trademark, unlike Firefox vs Iceweasel.

Thanks for the explanation!

From reading more about it, it seems these are all benign (in the sense of Chromium couldn't ship h264 because it's licensed but Chrome can).