You can't learn to swim by reading about water.

This is true, but is only part of the conversation. Learning about water might help build a knowledge base which can then be applied to the skill of swimming.

But the larger meaning I spun this into is you can learn about a craft to teach, be taught to do the craft, or both. Some can teach it but not do it. Some can do it but not teach it. Others can do both. So knowledge alone doesn't make you good at the thing.