I think there is only one thing worth answering in your reply:
Why not make an extension for people who need or want it?
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.
Is their mail server so different than any other generic mail server implementations? Do they encrypt all the emails at server-side?