Disadvantage? Certain steps in becoming a good musician are more easily done when playing by ear, some when consulting books. What you choose depends on you: what keeps you satisfied while you are learning? It doesn't matter if one method is more efficient if it bores you to tears. It doesn't matter if one method is less efficient if it keeps you happy while you keep at it.

Pick away at difficulties with your ear, with advice, and with books. If your ear and advice always get you through, good for you. You're in good company.