That's a useless use of cat.

This might be true if you're tight on CPU cycles. But in the evaluation process of the "correct" cmdline, I often exchange another filter with just "cat" for a quick check. You could argue that I could use "< some_random_file" instead, but on the beginning of a command line it's likely that I use the wrong angle bracket :-/ (It is far less likely on the end of a command line)