Are DeX really decentralized?

Could you elaborate on the concept of decentralization in the context of DeX, or decentralized exchanges? It's a commonly debated topic, and some argue that while DeX aim for decentralization, they may not fully achieve it due to factors such as reliance on centralized oracle services, governance mechanisms that concentrate power, or even the influence of large players in the ecosystem. Is it fair to say that DeX strive for decentralization but may not always fully embody the ideal, or are there specific examples where DeX have successfully achieved a high level of decentralization?