[the8472]

Well, ok, let's assume for a moment that ads are valuable to some users, perhaps informing them of a solution to a problem they didn't even know had solutions. That still wastes the attention of everyone who doesn't actually need that thing. Making it worth everyone's time can be incentivized by taxing eyeball-pixel-seconds. The numbers reported to the tax authority must be consistent with those reported to the advertising customer and the site owner. This way one would only place ads when it's almost certain that there's some unmet demand.