SimpleX Chat is an instant messenger that is decentralized and doesn’t depend on any unique identifiers such as phone numbers or usernames. Users of SimpleX Chat can scan a QR code or click an invite link to participate in group conversations.
-privacyguides.org
It’s clearly proving to be the most innovative technology when it comes to decentralized communication, in my opinion.
“Hang on let me write down my QR code”
Usernames exist for a reason, especially in chat apps. Not having usernames is only going to severely limit your target demographic. And if nobody uses your app does it’s benefits even matter?