It has always been...and will continue to be...the Cape's unparalleled tight geography that causes it to remain preeminent among wood bat leagues; that, plus a tremendous support structure underneath it. The fact that scouts can readily observe several innings in multiple locations every day is such an attractive drawing card.
It's the very same dynamic that makes events like the WWBA Championship so popular and successful; but spread over an entire summer in the Cape's case. It makes scouts so much more efficient than they'd be, otherwise; and also makes it economically feasible for clubs to commit scouts to the area for the entire season.