Magnetic contactors are useful in commercial and industrial applications, especially for controlling large lighting loads and motors, one of their hallmarks is reliability.
However, like any other devices, they are not infallible. In most cases, the contactors do not simply wear out from normal use.
Usually, the reasons for the contactors failure are misapplications, that's why you need to understand the basic knowledge of contactors.
When someone uses a lighting contactor in a motor application, that's a misapplication, the same is true when someone uses a "normal operation" motor contactor for motor jogging duty, contactors have specific designs for special purposes.