epoll doesn't change the fact that all of the well-supported I/O primitives under Linux are synchronous. Not necessarily blocking, but synchronous. There are aio_* system calls in the kernel but they suck. There are only a few, and the kernel devs seem to think that doing sync I/O in a different process/thread is good enough so they may not even last forever in the kernel.

Linux does not support I/O completion ports, or even a completion-based model for I/O at all. (Instead it uses the readiness model, requiring you to waste cpu cycles in a polling loop checking if an fd is "ready", that is if you don't want to spin off a new process.) In Linux you can't check an I/O buffer for data and schedule the call that would fill the buffer if it's empty in one system call, the way you can in Windows.

Windows was modelled after VMS, which was designed for reliability and throughput. Linux was modelled after Unix, which was designed so that Ken Thompson could play games on a scrapped PDP-7.