[Someone]

I think/guess he means that many vocal blockchain proponents are naive w.r.t. the 'decentralized' part, implying it would mean 'no government intervention'.

Gold is extremely decentralized. You can't know how much I own of it. Yet, governments started taxing it, so they had to track ownership (however crudely).

Paper money started out decentralized as bank notes (basically IOUs stating 'this piece of paper can be exchanged for G grams of gold at bank B'). Yet, governments started taxing it, so they had to track ownership, in the end making centralized institutions that govern how much paper money is made.

I don't see any reason why blockchain wouldn't go the same way (income in bitcoin already is taxed in quite a few countries, AFAIK; it just is hard to track)

Quite a few vocal proponents advocated the idea that bitcoin could solve (¿perceived or real?) social problems with technology. That's naive.