The author states: >"It’s beyond our scope to explain why, but this readiness mechanism really works only for network sockets and pipes — to the point that epo

The author states: >"It’s beyond our scope to explain why, but this readiness mechanism really works only for network sockets and pipes — to the point that epoll() doesn’t even accept storage files." Could someone say here explain why this readiness mechanism really works only for network sockets and pipes and not for disk?