Matrix is a graph not tree. Bluesky has a tree, yet no one cares to check and just trust the relay, after they found the tree proof too heavy and they clients don't care, Pubky doesn't use a tree because it would have required so much work and I knew no one gives a fuck not even in Nostr whether or not events are signed, you can always check the source of truth manually But a merkle tree is more than just a cheap signature over so many files, it also gives data integrity when you migrate, so you know you got all your files. So Pubky should eventually backfill that, but I can't tell them what to do. Peergos uses a Cryptree, but that doesn't just do data integrity, but makes encryption and read/write access control viable... Not to mention that Nostr Damus relay (Strfry) uses a database that is itself a copy on write tree (LMDB) ... Just not merklized. Of course all databases are trees, but LMDB is just flat out simple tree that could easily be merklized. So theoretically, you should assume that any database is a tree, and there are reasons to merklize it, and other reasons to encrypt it