There is no Firefox without people's desire for privacy. There is no sufficient privacy without people removing the diseased fingerprint of multiple big companies.
There is no possibility of a big browser surviving, without caving to big companies, in the artificially hostile web created by Google's monopoly.
And that last one is fundamentally unfair, beyond any accusation of "Derivative!" anyone can make.
I actually switched back to Firefox (from chrome) about 5 or 6 years ago because I liked the interface more. And I still like the Firefox design decisions more than what chrome is doing.
Privacy is nice too but people come to Firefox for lots of reasons.