Discord makes most of their revenue from selling user data so they probably want to keep as much as possible.

Do you have a source? That's a pretty bold claim, and I haven't seen anything else to back that up.

pretty sure they've directly stated that they're not selling user data

to be fair, you could say the same of facebook/google. they're not selling the data (giving it to third parties), but they're making money off it.

Sure, they serve said data to other authorized users and clients (intended recipients). Name a business that doesn’t do that. ;)

point is, their statement does not preclude them from using data for marketing purposes. some people are content with that, but others take it as a sign that they are (or will) use the data to build dossiers on users.