There are all sorts of things to think about before we get to anything like Wordpress or Substack "on Nostr". It's just more entries in more postgres databases (with relays and clients on top). Publishers will want to control their content. If we're talking bloggers and new sites, most of it is already probably in a postgres database somewhere. They are going to be worried about controlling their content if it's going to relays run by other people, etc, etc. X on Nostr vs. X plugged in to Nostr.