One Stack Exchange website on which I'm active has an ongoing project to fix the alt text all over the site to increase accessibility for vision-impaired users.
I'd just like to ask all of you to fix this before it becomes an issue, and include the alt text in any posts with pictures so that our content is more accessible to everyone. (This also means that we won't need to go back and fix this at a later point.)
You can run this query to find images on the main site that need fixing (although the database for the data explorer only updates weekly, so some more recent posts won't be there).
This is especially relevant for posts tagged comics, because most of the cited material in those posts will be in pictorial form.