It's silly to treat this like a totalizing partisan issue where everything must be clearly "pro-ai" or "anti-ai".
Browsers are currently incentivised to add a bunch of new features outside their traditional role. Some people prefer to keep the browser's role simple. It's not ideological and it's not "hating".
Most of the "AI" features added in Firefox makes no sense. They provide very little value to most people, but they are unreasonably hard to disable. Other than jumping the AI bandwagon, I have yet to understand why Mozilla keeps pushing AI features.
Microsoft and Google I can understand, they have AI products they desperately need to monetize or push to as many users as possible, because management bonuses are tied to CoPilot or Gemini adoption.
I don't see it as hating on AI, just because it's AI. It's not wanting pointless AI features in products that don't need them. I've pretty much disabled anything in the ml namespace in about:config in Firefox, because the features are distracting, but provide absolutely no value to me.
This niche will get smaller over time. The key hurdle right now is that most "AI" is just LLMs. People currently prefer to go to a website or open a dedicated application for AI inference. As better integrations with other workflows are made and people see them, the resistance will weaken.
Microsoft shoving LLMs into literally everything, including Notepad, is what people are currently hating, because it isn't quite ready.