This, of course, is the opposite of "no substitutions".
I had lunch at the Pump in NY today. The Pump is about 350 square feet (total) and it's a money factory. They have nearly 50 ingredients, all healthy stuff, and offer them in precisely 41,000,000 combinations. So, you can have whole wheat pita with egg whites, chicken breast and hot sauce, no onions. Or no pita, double egg whites, double hot sauce and brown rice.
People who care about what they eat go somewhere on purpose. People who don't care, go close or cheap.
There's a line out the door of the Pump every day at lunch. Why? Because people who love substitutions (the picky ones) go blocks out of their way to eat here. Is there anyone clamoring to get into the "no substitutions" place?