I see no benefit to CEX other than exchanging cryptocurrencies into fiat money, and banks can act as such gateways, so there is no real benefit to CEX. Some centralized services try to SCAM investors by saying that DEX means we will not ask you for any data and we may do it in case of scam, but it is still CEX as you do not control the private key and so CEX and DEX cannot be combined in one place because they both mean the opposite of the other.