The blockchain is saved forever on many computers. Your DMs are relevant only to two people (because encrypted), and only for a relatively short period of time. This disparity makes the blockchain a suboptimal place to store private messages.
I think using blockchains to hold encrypted data is sort of antisocial. It's "hey stranger, store this data for me forever, but you can't read what it is."
exactly the same case is with posts about news.
Correct. So conclusion should be... that others should benefit somehow for storing those messages for you for eternity. My project prio recognized that... that is why we want to introduce private paid priority messaging, and at the same time our public messages will be always free, because those messages contributes to common knowledge.
I really love your comment Sneak. I'll keep it in mind.