I believe Tonyaod has it right. It's more about the business than the lunch and it shows that you have a certain standing if you can order a large meal. I don't think it's good to be wasteful, but it's more about the show than the food in this case.

the days of wasteful business lunches are over. by decree. the tonyaod post is 9 years ago, most of the thread is over 8 years old. having resurected an old thread, i wonder if we can expect a serving of spam?