Yeah, like content addressing things you link to - to protect against them being changed (but not disappearing). 

 Arweave solves this problem with immutable hashes, served over a CDN of gateways 

 Hashed content cannot be altered after the fact.  So I think it's an important option that we would want to explore.  A good example of a protective hashed system is IPFS, which saves content hashes for any size file.  I've been wondering if something like that could be used on Nostr or integrated with Nostr at some point.