Apparently pre-rinsing confuses the dishwasher or something. Not doing it leaves me with residue all over the other dishes though 🤷
Interestingly, where I live I have never, ever seen a dishwasher installed with a hot water line. Even the cheapest dishwashers heat their own water, and around here we apparently always plumb them to the cold water for some reason, even though I'm sure plumbing to hot water would at least save time if not get better results.