Earlier quoted context omitted.
"You can lose everything overnight with automated trading." Didn't your father teach you about "Stop orders" You can't have your algorithm cranking away without supervision. And to be extra sure, lots of testing and LIMITS. Limit the amount and value of orders. With stocks, worst case: you lose the face value of stocks in your portfolio Derivatives: you can lose more, even 'infinite liability' (still, it's constraine…
Stop orders don't guarantee execution or any specific limit to the loss; During a flash crash, you'll realize that a "10% stop loss" order CAN become a 50% loss.
So I guess they have a role in limiting losses (which had they not been there would be much bigger)