Is it? The only people who should be deciding those limits are parents. If they fail to set and enforce those limits then any negative outcomes for the child are due to their own negligence, and can be adjudicated as child abuse per those laws.
The internet is full of amazing things but it is simultaneously a largely unfiltered cesspool.
Imagine you live in the suburbs, but at some point the house to your left got demolished and replaced with a casino that doesn't ID anyone. The house to your right got demolished and replaced with a liquor store that doesn't ID anyone. And the house across the street got demolished and replaced with the headquarters of a local group of political extremists.
Sure, there also happens to be an award winning library a couple houses down. But that's largely irrelevant when it comes to the question of how you're supposed to raise children in this environment.
And for reference, when I was talking about my personal experience, I wasn't talking about 80's. More like mid- to late- 00's Russia. The internet was already quite a cesspool at the time, the local IRL even more so. Just I wasn't interested. Once a teen is interested in getting into the edgy stuff there is no amount of regulation can stop them.
That's approximately my whole point. We have zoning laws. We have age verification laws. We have lots of ordinances about what is and isn't appropriate in public and around children and similar. You can't open a strip club across the street from a public school and I think that's a very good thing.
The vast global unfiltered internet is increasingly pervading our lives. I think it is entirely reasonable to enact minimal regulation that stems the tide with respect to a narrowly defined goal.