… and there are many Chromium forks out there. For web standards to really be standards and not “Chromium” there has to be a viable non-Chromium browser.

The illusion of choice:

You can have any color car as long as its black. I mean you can run any browser you want, as long as its Chrome.

If Firefox had 90% of the market would it be a choice?

Yes, because Mozilla can't force is onto it by making google finance and YouTube run like shit on competing browsers