Good examples are hard! I struggle with this when I teach, particularly because students have diverse backgrounds and goals. For example, I might choose to illustrate a particular concept using a very simple web application. But then I risk losing the students who don’t know anything about web development. I also risk losing the students who do not intend to become web developers and therefore may assume that the entire concept is inapplicable to them. On top of that, the example still has to be “good” in a general sense (illustrative, or persuasive, or both).