Nitpick, I live in the same neck, and I refer to it as “cafeteria style”. The only true buffet barbecue joint I’ve ever been to is Moonlite in Owensboro, KY. You grab a plate, and can make as many trips down the buffet as you like while grabbing as much as your plate will hold with the tongs (only place I’ve ever seen smoked mutton, and I’ll be sure to eat more the next time I’m there, and to skip breakfast). With cafeteria style, they charge for each item, and the only thing you’re grabbing are the plates that are offered.
I don’t know how cafeteria style became the standard in DFW, but it really is. My favorites, Sonny Bryan’s, Pecan Lodge, Longoria’s, Bailey’s and Heim don’t do it. Heim Longoria’s, and Pecan Lodge have you sit and wait after you order (if it isn’t to go), some Sonny Bryan’s locations I’ve been to have you stand around (e.g., the one on Mockingbird the last time I visited, who are open 24 hours now!*), but some have a cafeteria set-up. Bailey’s usually have my sammich prepared by the time I get done paying, but I’ve seen others standing around waiting for large orders. Dickey’s, Cousin’s, the generally departed Colter’s, and just about other place that starts up is going to use cafeteria style, though. I don’t have a particular dislike for it, it has its trade offs. If you are getting chopped brisket at the cafeteria style counters (I usually go for sliced), they ask if you want fat, lean or a mix (folks have preferences). Sliced customers usually get lean. I don’t see that kind of distinction being made about the cuts you get at the other style restaurants. I’ve often been served a fatty sliced sammich that I wouldn’t have gotten from a cafeteria style place because I would have seen it, and asked for a different cut. OTOH, more often than the others, the slowest way to get served barbecue.
If I were to guess how it caught on here, it’s because the high profit banana puddin’, carrot cake and chocolate pie look a lot more appealing when you’re coming down that line with your tray with an empty belly, and not when you’ve crammed it full of barbecue, onion rings and other sides.
*Those maniacs used to be only be open until they ran out of meat that was smoked on site the night before. It had it’s charm, but you usually had to get there before noon if you wanted to have a selection, and they were closed on the weekends by 3 or so. I don’t know if they started carting in meat smoked at other locations, but as a person who used to work the graveyard in that neck of the woods, it is a welcome change.