You can do single action lists in OmniFocus.
Do note, however, that OmniFocus is still designed to be a single-user application. It's possible to have multiple people using the same sync account, but that's not what OF is designed to do.
If you're looking for a multi-user product that supports delegation, you may wish to look at something like Flow (
www.getflow.com) which is designed for it (it looks more like Things, but doesn't have a native Mac app; it's native iOS app and web app). There are a number of other similar products, but I don't recall them off-hand.