DNS has always supported UDP and TCP. Traditionally queries used UDP and transfers TCP but this wasn't a requirement of the protocol. With the advent of EDNS an

DNS has always supported UDP and TCP. Traditionally queries used UDP and transfers TCP but this wasn't a requirement of the protocol. With the advent of EDNS and large responses such as those when DNSSEC is involved TCP was increasing being used for queries even before DoT or DoH. QUIC is UDP based so by being able to handle large responses DoQ reduces the need to use TCP and brings your vision of a UDP only DNS closer to fruition.