JMB, I would counter by saying that those three things existed long before the internet, they have always been there for those that
seek them out. I do not believe for one second that a person sits down on a computer and logs onto an undercover child porn site by accident.
However, it does work both ways. Because of the "open" nature of the internet and the free flow of information it is also easier to catch the people who do such horrible things.
This man was caught precisely
because of the ease in which information is available today.
Misinformation is nothing new either. It's been around since the dawn of time, gossip or the tabloid press for example. Imagine how garbled news used to be in the middle ages when it would filter across countries in what was essentially a massive game of Chinese Whispers
This is why I believe that every person should have the right to decide about what they see personally. A stupid person will make stupid decisions regardless of the quality of information they receive.
(Just by the way, I'm not using the word "stupid" as a synonym for "uneducated" in this context
)