I think this is more a case of there being limited appetite for what Mozilla is doing here. At least so far. I keep that stuff turned off in Mozilla and just don't see the appeal. And I'm saying that as someone who does agentic coding for some things, uses and pays for ChatGPT, uses perplexity regularly, etc. And I did install Atlas the other day. I didn't switch to it and wasn't too impressed with what it does.
I think browser makers (including the big ones) are still a bit struggling to identify use cases beyond doing search via a llm, adding side bars, and trying to find a balance between site security and giving all this full access to what's on the page.
Mozilla using their own limited models seems to have very little to add to this mix. At least my impression. But it's too early to state that user's don't want this.
Some users don't want this, clearly. And some other users really don't like any form of change. But there are other users that might want some of these things if they are well executed.
Anyway, Mozilla's attempts here strike me as yet another weak effort to do "something" that follows in a long line of half assed products and services they've developed, launched (sometimes), and killed over the last decades. I don't think they have what it takes; or at least, they have a lot to prove. And the vague hand wavy announcements for this aren't a great sign that they have this figured out beyond "doing something with AI".