Hard to say what's the cause or what's the effect, but I doubt the starter motor is powerful enough to break the ring gear teeth. I suspect the bendix hangs up, then when the ring gear tries to overrun the bendix, it puts too much load on the ring gear teeth and they break.
The bendix parts need some lubrication. If moisture gets inside the ignition cover and the bendix rusts or dries out, then the bendix will hang on release. Slow action will also mean missed starts.
Mangled (but not broken) teeth would be from too much play and the teeth trying to climb over each other.
Clash marks are normal on the bottom of the pinion and the top of the ring gear. This happens even if the flyweight spring is stretched. The spring stretching does help to provide a faster more reliable engagement.
It is still best to kick start the engine when it's cold outside. Once warmed up, the estart usually works OK.