I'm basing it off of announced 'closed for capacity' notifications. In previous years ive seen it several times throughout the event. Last year in particular, I didn't see it once. They could still hit attendance records, but they, at least according to my knowledge of seeing notifications, did not say 'sorry we're closed until some people leave'.So I'm not sure what you are basing that statement off of but I can say that BGW broke the attendance record for the park and then rebroke it again multiple times during HOS lasy year.
Also I completely agree as listed above that the park should not be caving to the few that decide to ignore the warnings. Although I'm not sure that they do as much as you think. HOS is not marketed as a family event. They have that during the day with the Count's Spook-tacular. HOS is an adult event. And adults spend a lot of money on alcohol during it. So if they bring their kids they are likely spending less than they do without kids on Alcohol.
But alcohol doesn't necessarily meet the same money spent on other things at the park. Families with kids will likely purchase more snacks and souvenirs, and play games and the like, more than a group of adults having a few drinks. I'm sure alcohol sales go up during the event, I have no doubt about it. But just on a larger whole, families are more likely to spend money than a group of adults.