The only move in WWE that is fully banned is the Vertabraker by Gregory Helms. It is however used by Homicide in TNA. The piledriver etc isn't banned, there are just wrestlers who prefer not to take the risk. For example, there is no way anyone will ever piledrive Austin again after Owen Hart broke his neck. Aside from that, if the WWE knows that it can be performed successfully and safely everytime by a particluar wrestler, then they are allowed to do it..