I'm saying people should build a chat app on top of the lightning network, not a chat app about lighting network.
Another thing to point out is the decentralization that comes into play in Lightning Network. It would bring 2 main disadvantages; [1] It would make private data somehow insecure, since it is stored in individual nodes rather that governed under a centralized secured server, and [2] Even though Lightning Network is faster than the typical blockchain in terms of response time, centralized servers are still much faster generally in performance, which is essential in having an app with the purpose of communication.