It's not just that, Dix. The heat aside, the area is literally dead all Summer long. The only places that get busy in Florida during the Summer are Disney and Key West.
Disney because of the kids, and Key West because a) It's not nearly as hot as the mainland during the Summer, and b) It's freaking Key West .
And I still prefer Islamorada
As Uncle Charlie used to say, "Never get into pissing matches with skunks."