I haven't really looked into this but just from my own random perspective, I feel like the delegations I send out bring me into the fold, as I follow the curators I delegate to and end up commenting on a fairly wide array of topics crossing a wide array of communities, where I sometimes pick up new followers or people to follow.

Regarding centralization, I do agree this is an issue I haven't questioned aggressively enough to get a satisfactory answer, and it is a concern for me. Some of the Hive Engine tokens I hold would likely be lost if one key person were to go rogue or otherwise vanish. I believe I have earned enough, and pulled enough out, to have my original investment back, but all profits are, as far as I know, ultimately not secure. I believe better smart contract implementation will resolve that in the future, setting those tokens up in more of a DAO like system, but I don't know anything for sure.