But these days, Chrome is plenty good enough for most people. Even if Firefox had a perfect privacy story and focused on their core users’ every whim, I don’t think their market share would grow.

This isn’t even getting into base level stuff like available engineering resources, or the scenarios where the other vendors often control or have deals to give them favorable distribution on platforms.

This isn’t the IE6 era. It’s a significantly different and harder problem.

You're presenting it as though any change would be met with hostility, but the alternative is that they're only met with hostility because they keep making changes that hurt the users. A little while ago they announced that they were working on properly supporting vertical tabs and tab groups; that wasn't met with any hostility. Of course, in the same announcement they said they were planning to dumb down the rest of the interface even more, which was. But the point stands; they can get a positive reaction by making changes their users actually like, they just don't do that as often as they do the other thing.

There would be value in being the only browser to actually stop when users tell them no. But they seem incapable of listening.

I don't see how trying to find a privacy-preserving way of dealing with the ad conundrum makes them not a privacy-focused browser/company.

You'd need to otherwise cite something re: undisclosed telemetry, considering the project is open source... so I'm not sure how exactly it'd be undisclosed.

IIRC, when Firefox started, it was very similar to the full Mozilla Suite with some features removed (which is not surprising, since it started as a Mozilla Suite derivative and they shared a lot of code). It has a long lineage going back to the old-school Netscape Navigator.