In practice, blockchain cannot be fully decentralized. Although the technology is revolutionary and aims to solve many centralized problems, it is not perfect. If theres no some control and regulation at all, we have to deal with such as FTX
Blockchain can easily be fully centralized by appointing some node as a master node which and only which can approve transactions. That's why there are many projects pretending to be crypto but which are centralized and that's why are not true crypto.
Fortunately Bitcoin is not built that way so direct regulation by governments is impossible and all regulations will be outside of Bitcoin's blockchain.