The lesson we learn from trading experience and articles we read are quite different, though the lesson from both are very important in trading but the mistakes of some beginners, they get much confidence in trading after learning only from books.
Experience gives the best lessons to traders, which beginners should never be in haste or be so confidence to trade with big amount of money by only gaining knowledge from reading books about trading.
I do agree very much with you. Books , articles, and YouTube videos can only teach you so much. They are infact passive learning. They real learning comes when you get your hands dirty in the live trading. The demo trading is the same category with books and articles. The the live environment the market is dynamic and changes happen fast, and you need to act fast. It is the experience gotten from these different expected and unexpected scenarios that brings about learning.