Admittedly it's uncommon - with maybe 5-6 incidences a month of meta of folks posting a selfie or 3 for no apparent reason, either as a question or an answer. There's no other text on these posts, and it feels like posts that are generally 'just' a link or image are unlikely to be of any quality.
Could we have a block on posts that only consist of images, and as an extension to that links?