I think the recomendation is aimed at people who don't leave for the break and then park-hop somewhere else in the afternoon. If you don't have a park hopper pass, you're not going to want to deal with the crowds that build by mid-day, so you're better off missing the morning EMH.
This is the truth of it right here, and yet another reason why hoppers are worth the extra money. Get in, enjoy the EMH, enjoy the mid morning when it still isn't too crowded, then get the heck out of there. Go have some lunch, take a nap, whatever, then hit a less crowded park in the late afternoon evening.
A lot of people plan on being up for EMH, but they don't actually make it early. But since they spent so much time planning which parks to hit on what days, they don't abandon their plans. YOU GOTTA BE FLEXIBLE!