The private schools are mostly in D2, but to your point, the leagues in the east do mostly make the private schools play AAA.
And I agree, the best player in the PIHL could be on any team really. I do agree with the other point that they would not put up the same numbers in AA as D2. I don't know if there is really much gap between D2 and A. In fact, the best D2 teams might be better than the worst A teams.
What is crazy is the A teams would easily handle the best teams from the 70s...back then, most teams had about 5 guys who could skate and filled the rest of the team with guys they played street hockey with.