Bingo. It doesn't just spread the park demand but also the stress on the transportation system.
Also, the real benefit of morning EMH is not just the things you can do within that time but also the benefit of being ahead of the "wave" of non-hotel guests cascading into the park over the first hour. People distribute in a relatively predictable pattern - nobody shows up at MK and runs straight to Country Bears - so by knocking out say SDMT and Space in the early time, you're on to the second tier choices with basically no wait as the GP is hitting the first tier stuff... and it's not until people start doing the tradeoff of a long Space/SDMT wait in the AM versus doing it later does the "wave" catch up to you.
Granted, this requires being dialed into smashing out rides at the start of the day, which isn't some people's MO.
They've probably realized that whatever yielding they could do by limiting reservations can be replaced by "better" variable pricing. Stinks that MK and Epcot on NYE will go back to being dumpster fires though.
