Do mods usually invite people personally on Discord? All the Discords I've joined have been via non-expiring invite links that either get passed around from hand to hand, or posted on DW or kept in the admin channels of sister discords; I don't even know who the mods are in some of them.

Whereas in a locked LJ community you did have to invite people personally, and IIRC it was some kind of three-step process where you had to invite them, and then they had to accept, and then you had to approve. The difference is that Discord doesn't have unlocked comms at all.