And yet many of these sites put enormous effort into combating ad blockers. So clearly the fact that users don’t want ads is fairly significant to them.
Users who don’t want ads aren’t exactly the same as users who are willing to pay. Prime example — myself. What I’m getting at, companies have calculated that in most of scenarios having paid model isn’t worth it. There will always be exceptions for services that people use a lot — Spotify, Netflix, Youtube and etc. For websites where you go on for a few minutes, people aren’t willing to pay up.