warlock patrons CAN'T be major NPCs because they'll only ever exist for warlock characters.
It's amazing how some D&D players believe every table plays using their house rules! This is total nonsense. The patron can be as big an NPC are the DM wants them to be. And some of the potential warlock patrons named in the official D&D rules actually appear in person in official D&D adventures.
I know all that, but this isn't a table with an actual DM that can work on the fly and talk to their players to weave everything together as it goes. This is a video game that was completed and handed over to players, and so trying to make a major NPC that only possibly exists in any playthrough, and make that NPC personally important to the character as well is something I don't believe Larian would do.
