It's the PBS/NPR model for web sites (i.e. "User Supported")!
This makes a great deal of sense to me as well. Some jerk advertiser - not naming any names (x10) can shotgun ads all over the web for its problems, maybe decide those ads aren't working, or maybe decide they need more attention ON their ads, and switch to an extra-annoying new scheme (the x10 popups were distributed on a banner ad network. Dunno if you all knew that).
As more people block ads and banners - as I continue to do for the major ad networks, just because I hate that my browser is a giant frickin' billboard otherwise - advertisers are going to demand increasingly obnoxious new ways to make people Punch the Monkey. We'll see things like Interstitial Ads - ads in the middle of mulitpage stories. We'll see Java or Flash based ads that demand interaction to view the content of the page (e.g. Experts Exchange, which, when viewed in IE, has a graphic that "falls" to the middle of the screen, obscuring the text behind it).
The saving grace to this is that anyone with any sense of decency will make their content available for the blind (and hopefully low-bandwidth users on modems and cell networks). If it gets to the point where every site is flash and all the ads are 200kb java apps, there will STILL be plain text SOMEWHERE for the screen reader programs blind folks use.
Anyway, back to the user-supported thing...
When I view a monkey-punching banner ad, I'm not REALLY supporting the site I saw it on. I'm supporting the ad network that served up the monkey-punching banner. The Monkey Puncher has his ad all over the place, and doesn't give a rat's ass about the site I saw the ad on. The ad network doesn't give a rat's ass either. If my site up and died, it'd be one less creditor that ad network would owe at the end of the month.
So who cares about my site? Only me, the person who visits it regularly enough to know that sometimes there's a Punch-the-Monkey banner.
As a little sidebar, I don't believe for a moment that I should have to pay to be advertised to. I hate going to the movies now because I see ads before the trailers. I never got cable TV because I didn't want to pay $50 a month to see 20 minutes of commercials in every hour.