Yes. It's a common teaching method (and not just in math) to teach simplified methods so that people can see them in action, and once students have some experience experimenting with them, delve into the underlying theory. I think it's a perfectly valid teaching method. Students should probably be past the point where they really think "Now I'll use FOIL" by the time they finish a class where it's used as a teaching method. But in any class, there are going to be students who don't really end up grokking the theory.