[zaarn]

The problem, IMO, is less that the file metaphor is not capable of expressing some things and rather that it expresses some things very poorly.

For example, a GPU device doesn't have like a file. You cannot effectively control a GPU via read/write. read/write are excessively slow for anything you'd want to do, including a simple VGA buffer. Almost all operations on a GPU in Linux involve mmap'ing it and then applying ioctl() liberally.

You can do almost everything using the file metaphor, Plan 9 proves it. But it's at times going to be a very poor metaphor that is better at working at all than working well.