You are describing local first apps, however they still need a server to help syncing when p2p doesn't suffice, which is often the case, but that is assuming you don't also need a datastore. There is only so much apps you can build without a reliable storage for user data, even if that storage is a laptop operated by one of their family... it doesn't matter. Then if you want to have large search indexes you need centralisation, but at least we shouldn't take a step backwards from WebDav, we should make it better; check Peergos for that, you probably will like it.