That depends on having an accurate count of how many people are in queues at any one moment. For each ride that averages an hour long queue or longer, you have other rides only 10 minutes long.
Consider that DHS, DAK, and EPC each have less than 10 rides each. So, how many people are in queues, 1,000? 10,000?
While there are considerably less people in the park at rope drop than at midday, traditionally (not counting DHS for the past few months), just how crowded is the park with all those people in the park but not in queues? The park is able to hold them.
And then let's consider DHS for the past few months packed at rope drop... it's not like there weren't large swaths of the park still wide open with almost none of the guests in the restaurants or shows.
All I'm saying is that using intuition to gauge just how impossibly crowded the parks would be if all the queues were closed isn't reliable. People don't have a natural intuition for gauging how many people are in a crowd and how an X number of people would make Y space too crowded or not.