Some people simply can't afford to pay for their bandwidth usage themselves, though. Think of the communities that used to use BBSes and now have forum sites where they post pictures, videos, and massive amounts of text. The owners, presumably hobbyists (originally), just want to share information, not foot the bill for everyone else who has a similar interest.
Advertising has a place. Personally, I can ignore most non-intrusive ads and they really only bother me if the move around following my cursor, or blocking the real content, which is more a problem with site or particular ad design than advertisements in general. Other people have a lower tolerance.
Make no mistake, though, what you're suggesting is just elitism trying to keep "poor" people from using the internet for its intended purpose, sharing of information. I'm sure that's not your intent but that's the reality of what you just indicated in your post. "If you can't afford it without advertisements, you shouldn't use the internet" is basically what you just said.