is simple what leverage is.
Someone, we call him bad guy cash in x amount of fiat. If Market maker 1 allows him to sell with fiat it is without traditional leverage, leverage. This factor x is how traditional markets work, and it will come more and more to crypto.
Remember: "IF big players come into bitcoin, it will become more stable".
It's always the difference.
@yabapmatt it would also work if they don't hold any coin to sell the coin, as long position can be resold and resold and doesn't get liquidated, they don't need to buy any.