They do, but not so much that your average home user would notice without having more than enough time to fix the problem.

Read it as 120TB at first and my eyes nearly jumped out of their sockets.

Mobile web interfaces for banks are complete shit, and often can’t be circumvented.

There are a bunch. I’ll see if I can find the exhaustive list, but you can look for it by searching “Firefox disable telemetry flags about:config” on your search engine of choice.

AAA games

There’s your problem – AAA games are shit

If you say so…

FireFox does collect some data, even in incorgnito, and even if you opt out of optional data collection. Last time I checked, you had to change a hidden flag (about:config) to truly stop them from collecting all data (and they could technically re-enable it in future updates).

Why do you even need that?

The thing about browsers is that there are so many accidental exploits already, it makes little sense to introduce your own on top of it.

And the one main issue with FOSS rears its ugly head – freedom of contribution also means freedom of bad contributions.

No, it simply isn’t. And even if it were true, there are people like me, who will gladly only be competitive in games and sports.

Not really, what it needs is a strong niche community with some reach