I think decentralizing and p2p is the wrong approach to solving the issue with commercialized social networks. What we really need is a non-profit & transparent & independent governance setup. Financing should happen through donations, maybe grants but certainly not ads. A bit like Wikipedia mixed with Mozilla, but even more transparent.
we need centralized communications even more than we need centralized file sharing. while we are at it, centralize the whole internet. heck, centralize and regulate every form of human interaction, digital or otherwise