My first job out of high school was working as a framer. This isn't that surprising. On my crew, more than two wacks would get you ridiculed.
Also note the way the nail sings when you hit it straight. You can hear that a ways off so you know when someone is singing wild by the sound of the nail.

"unless you like this sort of thing"

Doesn't everybody?

Very useful if you build a wood house and do wood work in general. Not really useful for a standard house, but maybe more like a cabin or work shed.

This looks about as safe as a chinese escalator....