Comment by strogonoff

Pedalling is the difficult part of learning to ride a bike. Balancing alone is not easy from scratch, balancing while pedalling is orders of magnitude trickier.

If you do not quite remember how it was when you were first learning to ride a bicycle, you may recall (or carefully experiment with) learning to ride hands-free, and note the increase in difficulty when you start to pedal as opposed to just coasting.

The advice to start teaching kids by taking off the pedals completely is perfectly reasonable as a way of making the initial learning curve less steep.