Second, decentralized exchanges are the only thing that can survive to government ban (you can't find a central failure point to hit). Particullary in case government regolarizes exchange and force them to adopt fiscal-individuation measures (know-your-customer, or KYC).
This is huge
I study economy at university and I have held a workshop about fiscal aspects of bitcoin, and preparing the exposition i have clearly understand this: Exchanges are the perfect gateway for governments. They are the only thing that can really centralize all cryptos and crypto users.