@Curator @RPBook @jerry @paulligas One more detail. Yes, anyone is "able" to add alt text but we are not prompted to do so whenever we upload and image; at least not for any of the instances I post on.
It should be relatively trivial to expand the upload dialogue box to include a field for alt text. This change would make a substantial difference both because of the constant reminder and because it isn't clear HOW TO ADD ALT TEXT in every instance.
Interesting, when I edit the post, I am given the opportunity to add a description but it is not clear in the UX that this is Alt Text.