Or you can a roster of C and D fillers around a few good, high capacity attractions. When did WDI last build something that can handle 3000 guests an hour?If were both talking about the same issue, that is, crowding, then...
If you are not expanding real estate, then the only solution is finding somewhere for all those people to be rather than jostling each other in the walkways. You could demolish current rides for rides/attractions that hold more people. But, unless you're changing a ride into a theater... I don't see that as much of a solution. So, if you're not expanding your park's acreage, how do you reduce crowding through the upgrading of attractions? My proposal of better queues does take up more real estate, which would tend to make things more crowded, but it packs people in more efficiently. A large, well-themed queue should hold more people than the ride itself.
If you are expanding real estate and adding more rides... and those rides are great rides, then you will draw in more people than the new area can accommodate and create more crowding... unless you build a large, well-themed queue... just like FoP can hold three hours worth of people in queue.
Of course there's also the Pressler Fastpass rule one argument but that's not going away.