You don't have to use just the POSIX-based APIs. There are io_uring, xdp, bpf, and more provided by Linux, for instance, exposing many more capabilities to user

You don't have to use just the POSIX-based APIs. There are io_uring, xdp, bpf, and more provided by Linux, for instance, exposing many more capabilities to userspace beyond POSIX-compliant APIs. You don't have to use sockets to do networking, you can get asynchronous local disk IO. What is the author waiting for, if it's the POSIX standard being too restrictive that's the root of all of their problems?