I don’t want AI in my Firefox. If Mozilla really adds AI, I will consider switching my main browser
Don't know why you anti-AI so much. An on-device AI is absolutely fine to me, and it's not like Mozilla will force you to use it. Remember the world is not about only you but also people having disabilities.
I think there is only one thing worth answering in your reply:
For web page translation, it is considered a very basic feature that should be there by default in all mainstream browsers (e.g. Chrome), but Firefox hadn't provided this feature for a very long time.
For any AI-assisted accessibility feature such as image tagging, my opinion is that it is even more important to make it easily turn on, rather than requiring user to search and download some extensions, which might be a too hard task for a disabled person.