This approach ignores all the aspects that made whatsapp / chat services popular in the first place. A short list:

  - Contact Discovery
  - Group chats
  - History / Log
  - Shared message order
  - Communication beyond text (emojis / reactions / inline images) 
  - Ability to receive messages while offline 
  - No need for technical skills

These aren't trivial features, they are prerequisites for any replacement, decentralized or otherwise. Just because we as developers like / tolerate things like IRC doesn't mean the rest of the world will accept it.