*Galaxy" You say that banning porn "wouldn't go down well with progressives". I am not sure what you mean by progressives, possibly people who are sometimes described as "woke". I think banning porn, online gambling adverts, the depiction of extreme violence, smart phones for under 16's, etc. would primarily not go down at all well with big business. It is the people who have derived great wealth from these industries who continue to object to bans, or even effective controls.
As to parents and carers being blamed for children accessing material that may be damaging to them, I think that is unfair and unrealistic. Of course, they should have some oversight of what their children are viewing, but, in my experience, children are really far more knowledgeable about these matters than their parents are. Often they know how to circumvent any measures intended to limit their viewing.
The young man who attacked the little girls and their classmates was obviously full of hatred and completely devoid of any sense of humanity - or fear of what would happen to him. Do people think he and other crazed killers were born that way? We need to understand what turns them into monsters and try to learn from it.
Things do seem terrible at the moment but I think we are forgetting many terrible things that have happened in the past. They undoubtedly caused terror but they were not then described as "terrorism". In 1996 in Dunblane a man killed 16 children and their teacher and injured 15 others. In Hungerford in 1987 a man killed sixteen people, including his own mother. And what about Harold Shipman, who has never been described as a terrorist but who is estimated to have killed well over two hundred people over a period of years.
Now there are calls for capital punishment to be re-introduced, despite the fact that studies showed that it is not a deterrent.
In my view, we need to see that whipping up more and more fear and hatred will not save us from these sorts of atrocities. We need to study and understand what turns innocent little babies into dangerous killers. so that we can try to take steps to prevent this happening.