Yet still, we have Rust (a phenomenally innovative programming language) that was conceived, as far as I understand it, to build a new rendering engine. I've not checked in on Servo for some time but they were going for full on ACID2 compliance with CSS, meeting the specs for HTML...A lot of that work became Electrolysis and then Quantum. Mozilla has been a serious lab for innovation without the conflict of interest in ad revenue.
Even if that effort has changed focus, the community now has Rust and I don't think we've seen such a fresh language paradigm since we got Lisp, Haskell, Ocaml, F#, Scala...
In which case, the world has benefitted from browser competition as a total side-effect of competing with the incumbent browser; we got the various evolutions of C and C++. Exactly the same way we got V8 and then nodejs and the whole server-side rendering paradigm with React and JSX.
If we all fall back to Chromium for everything, then Google has achieved a Pyrrhic victory. They need a disruptor to up their game... and it isn't WASM either.