It gets different when you are talking about denial of service attacks. Imagine everyone drove cars from the same brand, and one day a hacker discovers a way to

It gets different when you are talking about denial of service attacks. Imagine everyone drove cars from the same brand, and one day a hacker discovers a way to make them all stop. Then society is shut down. If 20% of cars stopped working, it's still a major catastrophy but you can work around it somehow. If you have robot armies or something it gets even more dangerous to put all your eggs into one vendor basket.