Not to take a side here, I can see both the benefits and problems either way...
But to the question "how do the academies draw?", it varies widely.
I have gone to games at Napa Valley College, where Prolific plays its home games, and have seen the 15-1800- seat gym nearly full... And I have seen it less than a quarter full. The players at Prolific all (or maybe nearly all) go to tiny Napa Christian for their classes, so many classmates from there go to Prolific games, but that's certainly not many with the super-small enrollment numbers there.
Their other local events, like Crush In The Valley, generally get quite a few fans.
I have seen other events online, like the one they hold at Paducah HS in Kentucky... Little town, small school, HUGE gym, like almost 4000 seats... In particular, I remember one year where there was a game featuring two top prep teams playing, like maybe Montverde and Oak Hill (can't remember for sure). That huge gym was PACKED! The very next game was two top high schools, once again can't remember who except that I was really interested, so there must have been a NorCal team in it, maybe Salesian... The gym emptied right after that prep game and the high schools played in front of mayyybe 500.
So, ya never know what's gonna grab people's interest...