The world is full of clueless people who run around banging into things.
While I would also offer to help if I was nearby, the extent of my sympathy has become limited. When you run around in ignorance and carelessness, bad things will eventually happen. The teen daughter is an example. She did it before and her dad lets her take the boat again? Duh! Was she texting at the same time? Hope he has lots and lots of spare cash because neither he nor his daughter seemed to have learned anything the first time around.
Now I also get how even careful people can ding a rock in this lake. I did it on an unmarked rock when I started boating here 20 years ago. It's an unfortunate cost of boating around here. If you stay in the main boating lanes the chances of it happening are far less. I explore other areas on a jet ski or kayak. No more propeller dings since.