Haha. Didn't Naruto learn the shadow clone technique from a forbidden scroll? That's about as much as I respect anything forbidden in Naruto. If something's forbidden, it only means you don't want all manner of rogues and enemies to possess it - just like nukes of our world. But still lots of people are going to harbour it. If we believe half of what Madara told Sasuke, Konoha would use the technique readily if it really was as powerful as you said. And even if Madara was full of bs, Konoha would still use it in a tight spot.