That's why there's two sides to the issue, on both ends positive and negatives.

Try to do everything yourself. Get your own water, food, make your own clothes, do it all yourself, no one is allowed to help you. Build your own road. Make your own car. That's the extreme of a world without specialization. You are taking it to another extreme to make a point, which I get. That's when people specialize too much, and that's the point of the post, for why generalization is needed. We outsource a lot, we do something in exchange others do others things. That's the basics of specialization.