Hmm...it's always been my understanding that a buffet is a style of serving food, not a way to eat it. What people choose to eat from the buffet is usually up to them (as well as what style they use to eat it).
12 slices does sound a bit excessive unless they cut the slices anything like the buffet style restaurants around here...paper thin and skimpy; a slice might weigh an ounce and for a hungry, good-sized male, that's not a terribly excessive amount. I've seen plenty of men who could scarf down a 12-16 oz. Porterhouse (with side dishes) without a problem if they were hungry.
Wonder if they've ever kicked anyone out for going back for too many desserts or rolls or excessive veggies? Probably not...those foods are relatively inexpensive and that's what they expect (hope) their patrons will fill up on instead of the more expensive protein offerings.
It's still a shame that once again, they make low carb sound like the "all roast beef all the time" diet and equally a shame that the wife is quoted as saying, "you can go there and just eat meat.".