The reason is that enrollment is NOT the only factor. We are simply talking about if it helps to have a larger enrollment, and the easy answer is yes. It is easy to bring up examples when there are hunderds of games that have been played. Like Highlands beating a larger school, or on the other side, Trinity being one of the largest enrollments and they are the best team in the state. Everyone knows that enrollment isnt the only factor in determining winners.
All I am saying is that if we are only talking about the number of boys at a school, it is better to have more to choose from. Just like it is better to come from a school with great community support, or a good coaching staff, or tradition.
I will compare it to the New York Yankees, they have the highest payroll in baseball, but they don't always win. As a baseball owner, would you rather have more money to spend on players? Sure you would, but it doesn't guarantee anything. There are many other factors in who wins a World Series or State Championship.