Where I think many people get weaker abstractions of this in their mind is where the OP hints: > and therefore a more accurate description of this feature is E

Where I think many people get weaker abstractions of this in their mind is where the OP hints: > and therefore a more accurate description of this feature is Everything is a file descriptor The filesystem is where files go to get names, and to be organized. But critically, not everything is a normal file, which I think is where people experience the most "the abstraction is leaky!" feelings. I don't think the abstraction needs everything to be a normal file, but I think there is still a lot of use in having a unified namespace for all the various types of files, normal or otherwise. (As opposed to having disparate namespaces for files of different types.) For the "file descriptor" half, the value is being able to wait on events/event completion for a set of heterogeneous file descriptors, but boy did it take a while to get there with usable interfaces for that.