Exactly so. You should learn to fly before you start having the radio do the thinking for you. The only way to educate your thumbs is through practice and developing a reflex and "muscle conditioned" response to flight controls. It also has trade-offs in that there are times you don't want a mix - and trying to find and flip a switch can be a disaster for a beginner. Invariably they look at the radio and take their eyes off the model.

Are you talking two or three channel with no ailerons? With full control surfaces the turn is initiated by ailerons . . . not rudder. Opposite rudder helps to keep the nose up, not the elevator.