I mean, we can add a "welcome" channel with a command that allows people to set a server-specific nickname, and it should be theoretically possible (though I'm not sure) to make it so that people can't post anything until they've done that.
I definitely get the frustration from not knowing who people are but I have no strong opinions one way or the other about whether or not we should put these measures into practice, I'll leave that up to group consensus. I would prefer that people use their forum name or referenced it in some way, but I'm not against people joining that channel through other means. People referencing their forum names being a requirement would help us distinguish who is and isn't already a forum member though, which would be useful for a number of reasons (a feeling of security among them).