"Decentralization doesn't apply to diet, our ancestors didn't eat random plants"

No, it doesn't. You connect to random relays and fetch only from specific authors from such relays, that's in one scenario. Then there is a different scenario in which you want to open yourself to reading stuff from strangers, in that scenario you choose relays wisely and take what they give you. That's the fundamental duality of Nostr, or something. @Constant has written many notes about it, made videos, even gave a talk about it. He explains it better.