Be happy the shutdown procedure doesn't start by opening regedit. I wouldn't be surprised, to be honest.

Not really

The -s stands for shutdown, with other ones being for hibernate, reboot etc.

The -t stands for time. By default it's something like 30 seconds. Putting it on 0 makes it instant.

It only takes two parameters to shutdown, how is that complicated?

Not really, it's a pretty simple command that not everyone uses anyway. -s is for shutdown, -t for time. There are more complicated things in the Windows command line interface.