Is there complementary `linux shutdown` and `freebsd shutdown` and `solaris shutdown`? If no, then this utility only increases cognitive load.

FWIW, I was installing Ubuntu and had an issue with Unity, so had to use tty to update and hadn't ever shut down from the command line before. It just took me one try of 'shutdown' and a quick look at the man page to figure out what options were needed.

I see this as either being used frequently enough to be easily memorized, or infrequently enough that a quick check of the man page is fine. The real benefit is that it's a very general solution that works on basically any system, and for a wide variety of commands. As another commentor pointed out, the apropos command makes this strategy even more powerful.

Why not just do `man shutdown` to figure out the option you should use, and then either set it up with an alias or just learn it permanently with repetition?

Exactly, that is the point. Also, some commands require several parameters and it's much better having the script asking for those parameters in an interactive way.

For example: mac ssh:download-folder

sudo shutdown -r now.

1) It's already muscle memory.

2) It's not hard.

3) Other *nix OSs use is too.