The problem is not search, it's curation. Any system that accepts everything will be overrun with things you do not want (fakes, *very* illegal things), and so there needs to be some authority that determines what is allowed. At that point, you are centralized, and hosting a website doesn't significantly hurt you.
This is also the problem with all distributed social networks. In the end, your options are formal centralization, and informal centralization, because absolutely nobody wants to live in true decentralization.
This is also the problem with all distributed social networks. In the end, your options are formal centralization, and informal centralization, because absolutely nobody wants to live in true decentralization.