More specifically: they chose Firebox because it doesn't have those kind of features. If the just wanted a (sorta-kinda) open-source browser filled with all the latest hype features they would've simply used Chromium.
Using Firefox is a political choice. People use it because it's one of the few remaining traditional browsers which isn't a tentacle of Big Tech. Chasing the competition and adding the stuff your users are actively trying to avoid isn't going to work.
> If the just wanted a (sorta-kinda) open-source browser filled with all the latest hype features they would've simply used Chromium.
I don't mind features existing, especially if I can switch them off if I don't want them. I definitely mind Chrom(ium|e).
I don't see how the existence of the Firefox AI sidebar gives Google effective control over web specs.
The main reason for using Firefox is because they support Manifest v2 / Ad-Blockers.
This increases security while also harming Google's business model. Win-Win.