Instead of a government blocking your bank account, they block your Coinbase account and all known addresses. Through financial networks, they tell every processor, exchange, and network to block your known addresses from transacting and impose heavy fines for negligent institutions.
Suddenly your "decentralized" bitcoin stops working everywhere unless you secretly stashed some under your bed. Which is the exact same situation that exists today.
The only difference is that promoting bitcoin enriches those with existing bitcoin investments.