Think of it like this: jumping in a Mario game is very simple. You hit a button, Mario jumps. But once you know how to jump, you can use this ability to jump over gaps, jump on top of bricks, kill enemies, destroy bricks, hit coins out of coin bricks, get mushrooms, jump on top of flagpoles to get points, and much more. Learning one simple thing unlocks a very deep array of options. These are the kinds of features you want in your application.

Oliver Reichenstein in a footnote comparing Facebook to Google+.