nobody thinks discord is e2ee. "private messages" usually means the same thing as "direct messages" -- messages between a defined set of people as opposed to an open group. You know and understand this term, you're just being a dick because you think that's an effective way to convince people to stop using proprietary software without basic features like e2ee. You're wrong.
You're trying to "correct" the correct usage of vernacular English because you feel like reinventing the language to suit your personal idea of what it should be. English is bigger than you. The phrase "private messaging" has meaning, and it's not up to you to decide what that meaning is.