There is a decentralized version of every service that Coinbase currently provides and many more they don't, with the exception of fiat on/off-ramps. Until regulations change that's going to mean centralized entities that cooperate with the existing financial institutions.

That fact alone does not invalidate the significant progress being made in every other part of this space with regard to decentralization. Once my USD are converted to crypto I can leave Coinbase and fully engage with the decentralized ecosystem, only going back to a custodian like Coinbase if/when I want to return to USD or other fiats.