For larger events, maybe.
For small ones, no. If you get people to bring food, people depend on them and they'll feel that they detract from the meet if they don't come. And having someone cook from the meet and people from the meet setting it up is a great way to social and meet people. Not to mention it makes it more than just a car meet. Whereas car meets that don't need food, plainly don't need food. In other cases, you have the same core set of guys that go to meets that enjoy cooking and sitting down and talking shit.

Having meet participants bring food and cook it kakes a meet mote grassroots, something about community. Bringing vendors in to cook and stuff takes away from that and makes it just another meet or car show.

My $0.02.