Does your answer suggests that there can't be a perfect decentralized crypto system?
Depends how "perfect" you are talking about. As gentlemand says above, Bisq is probably the closest at the moment to a truly decentralized exchange. However, it still has a website. That website is obviously being paid for, managed, and updated by someone. Although the code is open source and anyone can contribute to it, there are a core group of people who are managing the GitHub and merging pull requests. None of this is particularly dissimilar to bitcoin itself. Is it possible to be more decentralized?
Are you also saying that in the coming days, the government will regulate bitcoin and close it down if there is refusal?
A real DEX cannot be shut down by a government, in the same way a government cannot shut down bitcoin. They can ban it, make it illegal, seize the websites, etc., but none of that stops users continuing to run the software and communicate with each other. If a government is able to shut down a DEX, then it was never a DEX to begin with.