Three-Legged Products
A three-legged stool is the most stable of all seats because three points define a plane. No matter what surface it is sitting on, the three legs will find places to rest, and the stool will not wobble. It might be tilted and uncomfortable, but it will be stable.
One leg is not stable at all; two legs, stable on one axis; three legs, stable on both axes. But four legs (a chair) can be unstable if the surface does not match the lengths of the legs precisely.
So it is with product marketing: you need to provide some number of selling points in order to make a solid case. You must be careful in the construction of these points, however, because if you are too zealous and exaggerate the benefits, later selling points may interfere with or negate those that came before.
If you can't add any more selling points to your list without contradicting what you've already said, you don't have any more selling points. Or you lied. If you run out of selling points before the sale is stable (a two-legged stool), then you don't have a compelling product.