It helps some cases for sure and what I'd strongly recommend in practice. Connection pooling isn't always a viable option depending on the application though.

Connection pooling doesn't solve all the things we can improve by using HTTP as a base. We can be faster in just data transfer through compression, for example.

Using HTTP/3 starts to help tail latency that we can't solve with TCP. Unreliable networks with packet loss suffer greatly with TCP and not as badly with QUIC.