Exactly my problem with Duolingo. It is great for Vocabulary, but in the end it's just knowing it by heart, and I was suprised there are no real courses explaining you the synthax of a phrase or some other advanced rules.
And at least on Anki or Memrise you can select decks that match what you want to learn, such as getting the basics to order at a restaurant or ask for directions. On Duolingo I think I've learned how to say "the bishop sends a pineapple to the queen" before I learned how to say "bathroom".