Wranglers are off road vehicles. They do flip easy due to a combination of a high center of gravity and short wheelbase.
When you are a new driver, chances are higher that you will have an accident or at least have a close call with another car. New drivers lack experience in observing traffic behavior and lack other driving nuances.
When you drive a car that is easy to flip, you have no room for error. You can not take evasive actions the same way a more stable car can. What could have been a close call or a minor accident can turn into a major accident or fatality due to a roll.