why do we need teachers at all? Teachers are good for filling in gaps in your knowledge and/or clarifying a concept that you learned or attempted to learn from

why do we need teachers at all? Teachers are good for filling in gaps in your knowledge and/or clarifying a concept that you learned or attempted to learn from the text. All you really need is a good textbook and someone to talk to when you get stuck. If you can't learn on your own, how do you expect to perform any high-functioning job?