Few things infuriate me as much as someone posting screenshots or pictures of text pages and then just writing "screenshot of a text" or "a text page in a book" in the ALT text.
Visually impaired people have the same right to information as sighted people! It's not accessible to exclude us from the written content. And no, a brief summary like "a funny text about dogs" isn't accessible either. At least give some more details if you don't want to type out the whole text.
Stop excluding us!