There are so a many devs and clients on nostr, because nostr doesn't paywall them, there's no setup cost, there's not even a sign up.
a websocket connection
and that's it.
THAT IS THE KILLER FEATURE.
Awesome talk on this topic by miljan (npub16c0…6nvr) and PABLOF7z (npub1l2v…ajft) that'll probably end up on YouTube soon if you want to think more about it.