Yep, lots of people on the internet say "but what about the revenue of the sites you use."
If a site can't get by on its own merits then FUCK IT TO HELL.
Real good sites with real content can find some way to make money (such as selling t-shirts, subscriptions, or the occasional equivalent of a paid slashvertisment.). And if not, then just too freaking bad.
Do people realize that even in the real world, advertisers can't just do whatever they want? They can't throw branded rocks at your car while you are driving. They aren't allowed to put up billboard that may induce seizures. They can't tack sticky notes to you to see what branded rock you were interested in last.
Many communities have rules about what can be displayed where, and when. If the advertisers find some new way to be obnoxious then the community can fight back with new rules. Just the other day there was something on the local news about an area that was planning to prohibit stores from displaying large signs in their storefront windows.
So why should "cyberspace" be any different? If a browser has rules about what kind of content is allowed and where from, then who are advertisers to say differently?