I've asked a few, "and why is that?", and pretty much got "uhhh" as a response. Or, "that's how it's done."
Codswallop. It's a percussion instrument.
Use your forehead if it works for you.
I'm aware, of course, that different approaches will give you a different sound.
You can use fingers on a 6 string regular old guitar, too. Jeff Beck plays just fine.