Ah, recommendations… hm.

Just thinking out loud: what if, anyone who wanted to, could take a hash of their username, and make public all their interactions by listing the hashes of the usernames they interacted with. Maybe store it in a distributed database. So everyone could make a graph of anonymous hashes to run a recommendation algorithm in any way they wanted, but each one would only know their own username’s hash, so they could find out which hashes they could find personally interesting according to their chosen algorithm. Then, have people who wanted to be discovered that way, publish their user along their hash, so someone who found their hash through the graph of anonymous hashes, could find out which user it belongs to, and see them as a recommendation.