I think observanteens friend would have been turned off to yiddishkeit even if she was not abused by her parents and was emotionally stable. She actually said so herself when stating she saw hypocrytical behavior on the part of her parents. One need not be an einstein to spot a hypocrite.
I do think that “bad influences” are only legitimate threats if the one exposed has a poor foundation. Someone with a good foundation won’t feel threatened by the perceived peer pressure. The problem is, the peer pressure is enticing because there is the niggling doubt that perhaps those friends are not wrong. If a teen has no place to go with those little doubts he or she might decide to test out the water by figuratively sticking in a couple of toes first to try and get the answer on their own. Once that happens, all bets are off. As good an any yeshiva or bais yackov might be, how many of those students will admit to feeling comfortable approaching a rebbe or morah and asking straight out, how do I know the galach down the block is wrong when he asserts xyz? How many can actually answer that question if approached by the galach for an explanation why he was wrong?