Near the beginning of his explanation he uses the word "ideas" when I think he means "features". New gameplay ideas and new story ideas are the lifeblood of game creation. What I think he means is, don't load your first game attempt with unachievable feature lists. It's the best way to discourage yourself to the point of abandonment. Your approach should be to come up with game ideas that have reasonable scope and that are interesting enough to keep your attention. Sean is 100% correct in advising people to make simple games first. You don't even have to iterate on just one game though. You can make a simple platformer, then change directions with your second game. As your skill improves, you'll be able to accomplish more elaborate features in a shorter time window.