Duolingo doesn't force people to move on soon enough. If your goal is learn the language instead of playing a game it just isn't a good system.
If you are committed to learning a language you will naturally seek out the occasions to practice it outside the app. Duolingo doesn't need to 'force' you to do anything. It's not a parent, it's a helping tool. It seems that most critics of Duolingo have unrealistic expectations.