Certainly the pictures and videos on wikipedia which you chose to consider pornographic rather than neutrally informative have a different set of qualities then what you would find in the extreme sections of porn-serving websites.
Look into the Wikimedia Commons category "pornographic videos" and you'll see what I'm talking about. Not linking to it because I'm not sure I'm allowed to do that here.
There is a middle ground. You can give partial access.
Hence why I wrote specifically about the open Internet. You are right: there are ways to give people access to only a selected part of the Internet. If parents decide to do that, fine; doesn't have to concern any website operators, or any adults.