The key premise is that this is an important feature. I don't think it is that important to many users. Browsing poorly translated websites just isn't a thing.

The key premise is that this is an important feature. I don't think it is that important to many users. Browsing poorly translated websites just isn't a thing. Especially not with Google translate, which in my experience almost but never quite makes sense with many languages. About the only time it matters to me is when dealing with stuff I have to do (e.g. bureaucratic or legal things). In which case I prefer using deepl.com, which seems to do a better job of e.g. handling German legal texts. I guess in a pinch it's handy to be able to translate a bit of text or a web page but that hardly is a regular thing. Browser extensions exist for that. Also for Firefox. I don't tend to use those though because I just don't really need or want that.