What inadequacy? To say that a tool designed to facilitate anonymous communication is inadequate because people are doing things on it that you don't like seems like a pretty strange position. The inadequacy of a darknet is its uncensorability?
In freenet at least there is one significant inadequacy that you must commit your resources to supply others with material you strongly disagree with. The difference between having a network which others can use for trading CP and having a network that want's your bandwidth and disk space to serve CP crosses the line for many people.