Well, this would essentially prevent screenshot posts by extension. Unless you mean random, ugly ui elements but with no text in which case it wouldn't.
E: When mocking up new rules for the community I will try to write something to account for posts like those: https://lemmy.world/post/48711011
I intend to make a post in a few days with the proposal for new rules for additional feedback and to make sure that the community is on board and that nothing is too vague and such.
E2: Actually, after looking a bit more I think I will propose another one for allowing only image posts since there was a case(s?) of sharing an article link.