Not sure why you're bringing up drugs here. We're talking about webpages, not substances directly altering your neurochemistry.
But yeah, indeed - usually it's a fault of parenting. Instead of properly teaching about the dangers and responsibility (in case of weed/alcohol, or finance) they made it a tabu.
Point is, grown adults who "know better" fall into these traps too. It's not only about inculcation or knowing better. If it's there, despite all you know, sometimes you fall for it. That's the point.
That adults know better is a myth. They don't. It's not about knowing better, it's about being taught to be reasonable with the thing, and that takes long exposure to that thing, ideally with the support of a parent.
You don't get it. People trained, educated, fall for scams all the time. People in pen testing who know they will get hit also fall. There is a case for a moat or external protection.
But yeah, indeed - usually it's a fault of parenting. Instead of properly teaching about the dangers and responsibility (in case of weed/alcohol, or finance) they made it a tabu.