It's not, in my experience, a particularly common occurrence, but maybe a policy wouldn't be completely pointless?

I don't think a policy would be completely pointless. Because as a writer I sometimes I see art and am transfixed by it, but I'm usually much too shy to approach an artist and ask if I can write a story to go with their art unless I've already interacted with them.

A policy makes everything easier. I can just write a story to art and drop a link to the artist saying "hey, I did a thing..."

/my two cents