Last I looked there was no minimum number of clubs required. If you can play at a level that makes you happy with just a 5 iron, or whatever your favorite club is, have at it. Sounds kind of nice actually.
I have one, but you won't see it in my bag.........unless you pull the headcover off of it! I hide it out of shame But golf is expensive enough as it is, and that thing has paid for itself several times over.