Demo trading has a serious drawback in the sense that if you were to lose all the capital you had in your demo account, you can get it back with a single click, so a newbie trader can try as many times as they want until they get the positive results they want
That's a valid point, a newbie trader who's using a demo accounts gets the feeling that he/she can trade as many times as possible without losing anything because he/she can get his/her account refilled once it's emptied because of wrong trades.
Another thing to note is that with demo trading no liquidity is needed as it's done in a virtual way and that's why a demo trader's $1M market sell order may not dump the value of a coin while in actual trading $1m market sell order can dump value of a coin to huge extent.
I believe newbie traders should learn about those simple things and should only use demo accounts to learn trading interface so in future they can easily do trades by having the same interface. I even recommend traders to use trading view charts as those can be quite useful.