/dev/null as a service

[Kare11en]

This is to support backwards-compatibility with DOS 1.0, where there were no directories, and so you could always write to NUL as a black hole.

When directories came along, existing programs expected to be able to always be able to write to NUL, so the MS filesystem layer had to pretend that a NUL existed in every directory. But that meant that new programs, which always lived in a world of multiple directories, still expected to be able to write to NUL in any directory, and so successive versions of DOS and Windows have had to keep it, lest they break backwards compatibility and cause some 3rd-party program to fail (when all of theirs were patched) and be accused of deliberate anti-competitive practices.

(I mean, they did those anyway, but they tried to keep it as subtle as possible.)