Maybe, but I would argue that some of these features are genuinely useful and important. Take translation, for example. It's not great to have to send off a page that potentially contains identifying content to Google, but it is the easiest way to handle the matter. Firefox uses local AI to perform a decent translation relatively quickly, and I'd like them to work on improving that capability.
Many things that are not browsers are genuinely useful and important, this alone doesn't mean Mozilla should be doing them.