The exact opposite is true. The only consistently working, stable democracies do not have a single leader of the executive branch, e.g. Switzerland.
The CIA sponsored extensive studies on this and came to the conclusion that democracies with a strong presidential role are associated with a greater risk of failure. It's not really surprising, and it can be seen in the US right now.
The CIA sponsored extensive studies on this and came to the conclusion that democracies with a strong presidential role are associated with a greater risk of failure. It's not really surprising, and it can be seen in the US right now.