> 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.