You are right but it's confusing because there are two different approaches. I guess you could say both approaches improve performance by eliminating context switches and system calls.

1. Kernel bypass combined with DMA and techniques like dedicating a CPU to packet processing improve performance.

2. What I think of as "removing userspace from the data plane" improves performance for things like sendfile and ktls.

To your point, Quic in the kernel seems to not have either advantage.