Social games, that is, sets of rules, are studied under many different disciplines. Things have been tried. Experiments have occurred, papers written. We know some stuff about how different kinds of rulesets work. Sorry if you dont like the fact that others have studied and tested things, but that does not mean you get to deny their knowledge.
Matrix is a protocol, like xmpp or irc, not a platform like slack or telegram.
either you trust the crypto or you dont- crypted messages propagate to unintended recipients in many other contexts, what matters is who has the keys.