Groupon is waaay over valued. They have until recently been giving tons of stuff away. For example, everyone who signed up for emails telling them about new deals in their area would receive a $10 or $20 Groupon cash gift to use. This was widely exploited by people who frequent "cheating sites". These free codes were also able to be stacked on accounts. People have used this method to get everything from free dinners…
People have used this method to get everything from free dinners to free lasik eye surgery. FX: disapproval with a tinge of jealousy 8-/
Given that they are being valued based on subscribers and revenue, it's in their interests not to stop cheating. If you want to create 100 accounts, you're helping them sell this turd of an offering to the public.