Do you learn dancing from books too?

I recommend finding a class that speaks to you. A good teacher will make you get the right focus and postures.

I don't doubt that an instructor who can interact with you will teach more effectively, I was just answering their question. I would say it's possible but very suboptimal to teach yoga or dancing with just words. Illustrations and video improve on that.

People come from all sorts of backgrounds, with different coordination and relationship with body. Classes bring clarity of practice with group. With long experience, words or pictures may be enough. Otherwise the practitioner may be confused.