But what advantages does this have over Tor or I2p hidden services?
Cats should be skinned many ways. Different approaches are better or worse for different contexts. Also, surprising net-new discoveries are made beyond the frontier when you re-solve a problem with a new stack. Sometimes some property of the stack, in connection with the "already solved problem", reveals novel new territory. (Look at "the microblog UX" getting "re-solved" by Nostr)
Cats should probably not be skinned