Each blockchain has its own form of governance, outlined by its white paper, and actualized by the code and its supporting community. Since you're on Steemit, if you haven't already, I recommend reading the Steem white paper and/or blue paper.

Crypto is governance, and code is law. The whole point of crypto is decentralization.

Regarding your "criminals and terrorists" argument, that's easily debunked just by looking at human society in general. No system of government completely eradicates crime or terrorism, and crypto is no different. And depending on who you ask, certain governments are criminal and terrorist enterprises, and centralization is enforced through violence.