There is no substitute for theoretical knowledge and practical experience to learn any subject. Especially theoretical knowledge is incomplete without practical experience. I think theoretical knowledge is only one third of skill in skill acquisition. Then you need to complement the knowledge through practical experience.
If someone wants to claim to be a trader after learning basic trades, then I can call him nothing but a fool. Trading is very easy to learn but when you practice it you realize how difficult trading is. If you trade with two days of experience, you will lose many times more than you will gain. So it is better not to trade with cash without completing the knowledge.
You are right, when someone has gained theoretical knowledge of course they must try to practice what they have understood in the field they are studying because without trying it of course they will not know how far they have understood about what they have learned. When someone tries to trade of course they must be prepared for everything faced in trading and when they first try it of course they will fail because not everything they learn will be obtained when they first try it and over time of course they will slowly understand from the experience they get in trading, if someone does not have enough knowledge and is not ready to lose their money when trading then they can try it with a demo account and after they understand it well of course they can try it with capital that they can afford when they fail.