I completely agree with the op on all the importance of using a demo account as a trader, and it's also interesting to learn that even as a professional trader, it is still advisable to maintain a demo account through or where the trader can sometimes test new findings, new kind of analysis discovered new strategies and so on and on, personally, Ive never thought that a demo account can still be maintained and used for this purpose even after a trader has moved from the beginner level to an intermidiate to the professional level.
For me, I started trading forex before I discovered and came into crypto, I started trading forex by first practicing with the demo account for I think 6 months or there about, when I've built knowledge and became confident, I moved to live trading which involves trading with real money.
When I discovered crypto, I left forex and moved over to crypto, and with my knowledge of how to trade forex, learning how to trade crypto was a breeze, I had no need to practise with a demo account again, and never felt I needed it anymore, but with the idea op have shared here, I think I will open another demo account again.