Correction: When I specified whose lunch Groupon was eating, I said 'advertisers'. I should have said 'advertising agencies'. From an advertiser's perspective,

Correction: When I specified whose lunch Groupon was eating, I said 'advertisers'. I should have said 'advertising agencies'. From an advertiser's perspective, Groupon's pitch is really compelling. Instead of spending money on traditional media-buys to generate some interest and a few sales, spend the same money generating a lot of actual sales, and call it a day.