Not only decentralized currencies are making use of blockchain technology again. Although, it started from Bitcoin, while altcoins also make use of blockchain, now CBDC are also now making use of blockchain, but CBDC are completely centralized currencies. If you are relating it to decentralized currencies, just know that both centralized and decentralized currencies are existing for good reasons, decentralized currencies like Bitcoin as an alternative is the best, not a replacement but as alternatives.