And I wasn't talking about bitcoin specifically either, I'm just doubtful that you could have:
- A completely untrusted distributed "blockchain" style DB - Which would be fast and scale well enough to enable instant-messaging-style applications - While being almost completely free to use
Currently Bitcoin can process a few thousand transactions per block, every 10 minutes. In 2015 reddit averaged about 2 million comments every day: https://redditblog.com/2015/12/31/reddit-in-2015/
Of course you may say that you don't want to create reddit, just a small chat with friends but it doesn't matter: your blockchain is only as secure as its worth so if you want trust-less security your only solution is to plug yourself on an existing blockchain OMNI-style. Then if you want your messages to end up on the chain you need to pay more than the competition.