I agree with what you say, but how can we prevent kids to use those websites? Todays parents are too IT ignorant and they don’t know that they can protect their kids by using tools that they already have (parental control on smartphones and routers). So, how do we protect those kids? Pornography (for example) can do huge damage to kids.
Todays parents? No. The Boomer/Gen X parents of Millennials were also incredibly IT ignorant.
I know, but what were the risks there? There was no Internet! The firsts with wide Internet access were the late millennials.
I don’t know what you lived through, but there was wider internet access in the late 90s and early 00s that caused widespread panic amongst the boomers when I was a kid (born early 90s). I grew up in the era of the first social networks, MySpace being the biggest early one I remember. What surprises me more is that so many millennials have grown up to be just like their parents in that regard.

In fact I wrote:

The firsts with wide Internet access were the late millennials.

which seems to be you.

Yes. What is your point? I was commenting on the fact you thought this was a current parents problem when it’s been a problem for over 20 years now.
My point is that you can’t compare today’s problem with 20 years ago! 20 years ago the access to the Internet was through the home PC for the amount of time the kid was allowed to use and with people in the house (usually); today the access to the Internet for a kid is 24/7 and everywhere. There is no comparison. Parents should be more present in the kids life? Sure! Parents should block Internet access to porn website at least until a certain age? Yes! But most of them doesn’t even know that ths is possible. Maybe we (society, givernment) should work more here.

You invoked the comparison by using the phrase “today’s parents are too IT ignorant”. If anything, they know more about tech than ever before.

Edit: In response to the rest. Parents just don’t want to have uncomfortable conversations with their kids, they never have. Because, no, it isn’t actually easy to block all pornographic websites reliably.