Even though I use Firefox and upvoted your comment, I will also say that it's good for this to exist.
A monoculture of Firefox would be just as bad. In fact there are already right now reasons to use various "de-mozilla'd Firefox" forks instead of Firefox.
Ie the same effort as this even while using Firefox, so that effort doesn't actually factor into anything.
We’re so far aware from a non-Chrome monoculture, though, that this feels like saying an ice age could be as disruptive as global warming. Right now Google can dictate what happens on the web, and using Safari or Firefox is better than any browser engine which is controlled by Google, including this one.
I personally use Safari for performance (going back to Chrome adds noticeable jank even on an M2 Max) after using Firefox for the 2010s but the key part here really is centering on web standards.
It doesn't matter that we're not in danger of a FF monoculture. Totally irrelevant.
At one point Chrome was new and people said "just use Chrome" and at that time they were far away from a Chrome monoculture. It also doesn't matter that Google then and Mozilla now are in different universes of scale.
It is a value to the world to have even a mere proof of concept chrome compatible browser that has as little Google or MS special input as possible, even if that isn't 0%.
A monoculture of Firefox would be just as bad. In fact there are already right now reasons to use various "de-mozilla'd Firefox" forks instead of Firefox.
Ie the same effort as this even while using Firefox, so that effort doesn't actually factor into anything.