Here's one example - let's say you have a circle somewhere and you want to edit it to make it a wiggly shape, but you know that later on you will want to snap other things back on to the center point of the circle.

But once you edit the circle to make it a wiggly curve, you won't be able to get a center snap on it anymore.

So in this case you could place an individual point object at that center point, so that you can snap back there later on. They're basically reference markers for snapping.

You don't typically need to use them very frequently, but sometimes they come in handy.

- Michael