This question relates particularly to SE Biology, but has aspects that impinge on other Stack Exchange sites. It concerns insertion of images and their viewing by users who use screen readers.
Is it, or can it be made, official policy that posting text as images only is not allowed?
Can better technical support be provided so that text descriptions can be associated with complex diagrams in a form that is best suitable for screen readers?
It seems to me that the answer to the first question should be simply “Yes”. I often comment to lazy posters who photograph some homework question (that is probably off-topic anyway) saying this is against SE Policy, but I am rather whistling in the dark. I haven’t seen it stated explicitly.
The second question requires practical changes in SE. I do not use a screen reader so do not know what is technically required, although I have been involved in designing websites and following guidelines on accessibility for the visually impaired. I do use diagrams frequently in my answers on SE Biology, and find them often indispensable for a good explanation to sighted readers. I hope that they complement my text explanation, and sometimes when they don’t I have written a summary for screen-reader users, but it would be better if there were a pop-up box associated with adding an image so that this could be done in the best manner.