You may have noticed that in my photo albums, I put what may seem like too much text in my alt tags. This is because these pictures are meant to be admired purely for their visual content, but for any number of reasons, you or I may not be able to view them. These reasons could be blindness, data corruption, or an archival process not deeming my site worth the extra space.
It would sadden me to no end if for any reason I could not experience these photos in at least a nominal way again.
To be clear, not every photo or picture on a website should be described in this way. In fact, to most people using TTS, it only hinders the usefulness of a page. A "next" button should at most say "click for next page". A meme should be described in terms of what makes it funny, not in every single trivial detail. But these images are nothing except for their details, and I want to impart them in the way that I know them.