No, she said they had trouble with people leaving without paying.I think the manager meant "eating-on-the-run", not "dine & dash". Many Disney enthusiasts, ourselves included, do not like to waste time waiting for the check. I always ask for the bill when the servers bring the food, so everything can be paid and signed before the last bite is taken.
Asking for the bill when a plate of food brought to you, could be all you are eating. I haven't taken a poll, but I think most people with a buffet , take more than one plate. For myself, I like to take a bit of this and that and go back for what I like.
When we go to a meal to disney, we intend to enjoy the food. If we wanted to eat and rush out to space mountain, we would eat a bagel in the room.
Like I said this was the only time this happened.