It did sound familiar ! Tor FAQ has something in its abuse section about how Tor is not just a big botnet to be used by anyone who wants to DDoS a target, or amplify the bandwidth output of their botnet. This is true! However, the original poster grossly misinterpreted this as meaning that hidden services cannot be DDoSed, or that DDoS attacks can not be carried out through Tor. What it really means is that, although some things , like UDP based DDoS attacks, cannot be carried out through Tor, that other sorts of attacks are not MAGNIFIED by Tor or made POSSIBLE by Tor. Tor can be used for anonymizing the source of a DDoS attack though. And DDoS attacks against hidden services are possible in all kinds of ways.