Together with the hope that the OS will clean up (and close) all handles created by a process, this means that a pipe should vanish once the creating process exits.

Under normal operations, a named pipe server will DisconnectNamedPipe() any existing connections prior to exiting. If it doesn't do this because it is killed, then remote clients don't know the server has shut down and so may leave the connection open. Hence the pipe name will still exist in the namespace which can prevent the server restarting.

At least that was the explanation given by a vendor for a product failure under NT4 several years ago. Dunno if it was an OS bug since fixed.