The importance of child locks

I'm going to jump straight in here with a story.

I have a friend of a friend who's child had an inappropriate experience with another child. This other child comes from a family that do not have child locks on their internet devices (computer, iPads, mobiles phones) despite the fact that the father of this household is heavy into online pornography. According to his friends, the type of adult content he views is beyond the standard, the more shocking the better. Not that is would necessarily make a difference if the content wasn't mainstream.

The children play on these devices and have seen this adult content and not being able to understand what's going on, the young son, tried to act out some images with other children. Parents were told and a conversation ensued, yet the parents in question downplayed the incident and still refuse to put locks on their devices. It seems they don't see this incident as that bad a thing. Heaven knows what the wife/mum makes of all this?
Talking about this incident with my friend I mention how there have been more and more incidents reported where young children try and act out the images they've seen online. For example some young boys in he US sodomised another boy with a pen after watching adult content online. My friend downplayed the incident, claiming only children willing to hurt other children would do such a thing. The truth is when children view adult content, they don't really understand what they're viewing, so they reenact what they've seen to try and make some sort of sense of it. Them not understanding is to be expected. Introducing adult content to inappropriately aged viewers can have terrible consequences. 

The point being: it is SO important and necessary to put adult locks on your internet devices. SO important! As adults we barely understand the images we're viewing (although we think we know what's really going on), so how can a child who doesn't understand sex in it's full context understand what they've seen. Especially non standard images such as hardcore or violent pornography.

Pornography is damaging on many levels; it is addictive and alters brain wiring, viewers often report impotence and unable to perform sex with real people, content can be violent and shocking (hurtful to those taking part - mostly females - and causes PTSD). If, as adults, we don't fully understand this, how can we expect children to be able to process what they're seeing.