Pet rats food?

When I got my rats (from a proper store that houses many different kinds of animals, has people in store who expertise in each type of animal) the guy said the store feeds their rats hamster food and this is fine for them. I've just been looking through a list of good and bad food for rats and hamster food is listed as bad in numerous places. It says to not feed rats any food that's designed for any other small animal as it doesn't meet their nutritional needs... and yet in the store they fed all their rats hamster food. then there's also people on forums etc are saying they've always fed their rats hamster food? IM CONFUSEDDDD halp