This slashdot comment from pete-classic is spot-on.

There is a more fundamental problem with advertising.
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When the users of a service pay for the service, they are the customers, and the service is the product. When advertisers pay for a service, they are the customers, and the users are the product. The service itself is relegated to a loss-leader; bait to attract users so they can be sold to the advertisers.
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This is one of the primary reasons why TV is such a wasteland, while the DVD landscape is so rich.

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every time I try to tell my myspace/friendster friends why I don’t trust the service, most don’t understand. So there it is!
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P.S.: I collect bright slashdot comments for quite a while, first by memepalm, then del.icio.us and now by twitter. it’s all about double filtering, heh?