Not quite. Poggi recruited from across the country for athletics, and brought in kids who were physically exceptional - much bigger, stronger, and faster than the other kids in the MIAA.
Poggi did not recruit from across the country at Gilman - he recruited initially from the counties surrounding Baltimore, then expanded to the DMV. He didn't start recruiting nationally until he got to STF.
It was costly - the coach insisted on a certain number of scholarships each year in order to feed the machine he built.
No, he insisted on a certain number of slots for football players; not tuition. He and donors covered the tuition expenses. And I assure you Gilman wasn't worried about any cost.
It caused problems in school, as many of the recruited players struggled with rigorous academics.
Many? Again, this is untrue. Look at the schools Biff's Gilman kids went to. His last team at Gilman sent 2 kids to Stanford, 3 to Navy, 2 to Cornell, 1 to Michigan....
Other schools complained, but the MIAA couldn't do much. Eventually, the other schools saw the only choice was to opt out.
Notice they didn't stop playing the other MIAA teams - just the one that had an unfair advantage.
Eventually, things changed. Poggi moved on. The other MIAA A conference teams returned to playing against Gilman.
To reiterate, no MIAA teams ever opted out of playing Gilman. That didn't happen until he went to STF.