I love that whenever duolingo is mentioned all the armchair educational psychologists come out of the woodwork claiming that duolingo sucks because it's too easy or too much like a game.

One of the most valuable determinants for learning a new language is regular practice. Answering 30 easy exercises correctly will do more for your language skill than 10 hard exercises of which you only answer 5 correctly.

And easy questions have the added benefit of being less tedious and convincing more people to stick to the app.