I think Groupon's model preys on small businesses unskilled in accrual accounting and pricing strategy. Also, both my readings and personal interactions have given me the impression that in their hyper-growth they have become a deeply dishonest organization.

All that said, however, there are still some interesting non-predatory wrinkles in their model.

The single deal at a time served to create consumer focus. The trigger threshold gave merchants confidence a deal would have a certain minimum impact. The time limit and trigger threshold served as an especially powerful call-to-action: now or never.

Though Groupon quickly tuned things (and grew) such that every deal was essentially guaranteed to 'tip', the group-threshold-mechanics were important for accelerating early adoption, overcoming vendor- and consumer- resistance to coordinated action. This mechanism, rooted in economics and game theory and related to the 'assurance contact' concept, still has utility for other endeavors, among them Kickstarter, even if that mechanic standing alone does not provide any sort of defensible advantage.

By all means, throw out the baby. But don't forget there's still something interesting in that bathwater.