The Internet is different from the offline world, though: Costs are far lower, which means there's no economic incentive to exercise self-control. A junk mailer can send out millions of untargeted e-mails for practically nothing (which is why I get invitations to metallurgy conferences in former Soviet republics whose names I can't spell), and a made-for-AdSense spammer can vomit millions of computer-generated pages onto the Web without having to think twice.
Since this is the AdSense forum, let's leave e-mail and other forms of Internet spam out of the discussion and focus on Web advertising (specifically excessive AdSense advertising and MFA sites). Regulation isn't going to solve those problems; the solutions must occur on three fronts:
1) At the user end. (Ad filters, better-educated users).
2) At the search engines. (Better differentiation between real sites and MFA sites; more aggressive filtering of questionable pages.)
3) At the ad networks. (More aggressive policing of MFA sites by Google, for example.)
I can see two measures that could prove very popular with users and could provide an incentive for site owners and ad networks to exercise self-restraint:
1) More widespread use of ad filters. For example, Firefox could offer ad blocking, not just popup filtering, possibly with different levels of filtering (as described under point 2 below).
2) Search-engine controls that would work like spam filters, allowing users to specify anything from "unfiltered results" to "block all commercial sites or sites with advertising." After a bit of experimentation, even mildly Web-savvy users would find what levels of filtering were appropriate for them, and--over time--owners of Web sites would learn to either practice self-restraint or settle for a much smaller chunk of the Web audience.