Sounds like it has the same value as saying "I used to own this one famous painting before it burned down in a fire."
A hash corresponding to the bits in your file? Sure, that works, you can say "yep, this is the image, I own it." A URL plus a hash + the bits. Sure, that makes sense, even if the URL goes away, you can prove that those particular bits belong to you. A URL that's now dead and nothing else? Nah.