Almost every machine in the world participates in at least one peer-to-peer network: Windows Update. There was a time when the Steam client also used bittorrent technology, not sure if they still do.
Obviously P2P gets used in various things, my point was just, that (most) people likely won't willingly join P2P networks to fight "censorship" or help archive things with questionable content or tainted with potential copyright infringements.
