...it was mainly Rand who thought of it, and who carried it out. No one else would have even attempted such an enormous undertaking (or suggested it to Rand or whatever since they would have just thought it impossible). And its commendable that he decided to join in a mixed gender circle and release all that power to Nynaeve at the start. I would say it was 75% Rand who caused the cleansing, not only the act, but the actual decision to do it, and the plan on how to do it. Hence if the cleansing was anybody's success it was firstly Rand's success (his greatest one). How he achieved that success is by doing something no one had done in 3000 years (saidin and saidar).