Sentencing a sex offender, the judge said: "You've been downloading indecent images of children for more than 20 years."
This may not be using the web much if at all. Back in the 80s and 90s people used to run bulletin boards out of their own homes. It was a pc connected to a single phone line. One person at a time (or more, if there were more lines) would dial up, read the messages, add their own messages, add files, download files. A group of paedophiles could find one of these servers and communicate completely anonymously, sharing illegal images and stories, without anyone ever being able to identify or trace them. It's possible the bulletin board owner might have been unaware of this activity.
Similarly, people used to crawl the internet open FTP servers (think of it like a network drive). Then they could anonymously drop illegal images there, and share the address quietly in chat and they could exchange files again anonymously. Think of it as a
dead drop if you are a fan of cold war spy novels. This would definitely have been without the knowledge of the person running the server.
These days it's probably more on the dark web, which is a road I haven't been down.