There are other parameters that are useful when evaluating a configuration besides just speed. Resilience is one of those, as is long term availability. Torrents seem to do quite well in the resilience department, I'm not sure how well they do when it comes to long term availability. Maybe someone has already studied that, it would seem to be the torrent equivalent of 'link rot', and quite possibly it is very high.
Sorry, what I meant by speed is: the ability to quickly access small sized resources such as HTML pages. The initial handshake required for P2P systems makes this process slower. Obviously for larger files where there are lots of peers serving the content, you can get better speeds.