I don't think the reasoning you give is suffice to explain the correlation of BitTorrent's popularity and the absence of a search function. In fact, you still do have to search for content, but you search for it on different trackers (which must be known or be able to be found to begin with) - thus supply of content and the searching for content both became decentralized - one of the best arguments for BitTorrent, since previously most central networks were easy targets for corporations or lobbyists and could just as easily be completely shut down.