I agree a successful business need not be unique. For example, many blogging platforms are and will be successful (e.g., tumblr, posterours, blogger, wordpress, etc).

However, if the consumer value proposition is built on providing exclusive deals, than to preserve your audience's trust, your deals need to be exclusive.

Please note, the article was also about how Groupon: -has no top not repeat local customers -has inside investors selling -benefits from a temporary trends towards coupon redemption