I've not seen it at all but you're right that there are some strange attitudes with some people and letting their children watch horrific things at a young age. Even on this very topic, some of the comments are "meh violence isn't a problem, I don't see why it would be disturbing to my child" which is clearly a case of desensitisation influencing the stuff they show to their children.

I have same many films that I wish I had never seen as I can't "unremember" things or wipe bits of my brain out. The incessant flow of violence in films only serves to desensitise: something is truly shocking the first time, not so the next time, and repeatedly it isn't shocking anymore.

To see that some people use their own level of how shocking a film is to THEM to decide whether to show it to their children is distressing; "I wasn't shocked, so why would my children be??". Very sad.