How do you know that the last statement is not true? Are you maybe confusing your opinion with fact as well, maybe?
Sorry, just making a point that you seem to be just as snotty about your own "facts" as you criticize
@ford91exploder for. He never said when all the restaurants were open, but I asssume was talking about YEARS ago. That would have been when everything was open.
Anyway, I am interested because I was about to say something similar to explorer but he beat me to it. Not so much about the profit margins line at the end, but about the idea that people will skip meals when the line is too long, but will spend more if the opportunities are more frequent. This is a basic concept from business school, especially impulse buying combined with the marketing concept of "location, location, location." In the case of fast food establishments in a theme park (captive audience), there are not only people who HAVE to eat (and thus WILL wait in line, no matter what, just as you suggested), but there are also people who are (1) on vacation and more open to splurge as the opportunity arises, and (2) teenagers and kids or adults who will yield to temptation (impulse buying) if it is easy but not necessarily if their MM+ fastpass for the next ride does not leave them time to wait in a long line.
So, the canibalism concept is only partly true. For amusement parks with wafting smells of nearby eateries, I would say that the impulse buying concept is just as big as the "need" to find lunch somewhere. And the "location, location, location" concept adds to the impulse sales. The together add to MORE sales overall, EXCEPT that impulse sales are usually diminished significantly if the line is too long (and the opportunity cost of one more ride in your $100/day theme park is compromised).