Permanent storage is a harder problem than many people give credit: it costs money for storage and for access. When you have a little bit of data used by a few people, you can probably find volunteers on the internet who will donate capacity but that falls apart once a service becomes popular enough that people have expectations of reliability or support. It also becomes legally a minefield the first time someone puts copyrighted or illegal material there, so nodes are going to become selective about what fraction of the total they mirror.

This seems like a challenge for artwork since blockchains are so inefficient compared to the alternatives and for any one person it's both cheaper and more reliable to store their collection on a regular storage service which has SLAs. Why pay more to take on other people's problems?