The only flaw i can see right now is its all negative. one could argue that for example someone could have been a wife beater and a drunkard and the wife because of cultural or other reasons put up with that situation. Then the husband studies the bible and turns his life around and becomes a great husband. His interpretation has a very positive outcome so in his particular case the said religion or cult has not been DANGEROUS but has been greatly beneficial to him and his family.
Things aren't always so black and white. Yes, in this case it's possible that the cult could actually help someone. That said, it is my strong opinion that there is always another avenue of support/help that would be of greater benefit than the cult would be, without the strong side effects from being in the cult. There are groups that will help a person who beats his wife or who drinks that don't also, for example, require you to sign a card that states that you will give your life in support of the group should you need a blood transfusion.
The cult is like heroine. If you need to undergo emergency surgery and heroine is all you've got, it might save your life if the surgery is performed while you're doped up. It would, however come at a risk of addiction that could later ruin your life. It would be immensely better if modern anesthetic were used. Just because heroine could help someone in this case isn't a reason to advocate for its frequent use.