That's a guaranteed way to make trading a meaningless game - and to lose money in HUGE amounts as soon as they go live. There's a balance to everything - and while I understand the point you're trying to make, "demo trading for many years" is way, way the hell past the crazy side of the pendulum swing. Trade demo until you no longer make stupid platform mistakes and at least think you understand the basics of what you're doing, then trade small - like really small - amounts. Losing $10-$20 again and again, especially when you believe that you should win instead of losing - that's the best teacher. One that gives you black-and-white feedback about whether you're RIGHT or WRONG, in a 100% real scenario, with no comforting lies of the sort that demo trading feeds you. If you can put your ego aside and listen to that teacher, you'll grow as a trader. If not... well, trading isn't for everybody.
I think both sim and small size trading are better for learning vs starting large. If traders were patient, they might: Trade sim only until they get consistently profitable by a bit, or double the sim account After sim success, do 1-share trading for a long time to learn order routing, the joys of slippage etc Slowly increase size But traders aren't patient, so they trade without being trained, too quickly, and lose $.
Baptism by fire is the only way to learn. It's a nice luxury if you can start out trading someone else's capital....then go on your own and trade your own money once you've figured out the game.