Many many guys in this hobby have learned how to fly without using the rudder. I would say that over 70% of guys in your average club don't use the rudder, or use very little, except on the ground to steer. Many park flyers don't even have rudders, and that is where a lot of guys are starting now. This is fine for park flyers and small aircraft, with small props. However, when a guy wants to move on to larger aircraft, with greater mass, larger engines and larger props, he soon learns why the rudder is so important. He learns the word yaw, and all that it intales. He should have learned this early in his instruction, but usually doesn't.

The rudders on most dedicated trainers are not all that effective. No reason to ignore their existence. Instructors, do your students a great service and teach them ALL the functions of control on the trainers so equipped.