Ironically, it's also an interesting commentary on how quickly groupthink and follow-the-leader actions take over on social news sites.

Did everyone who originally downvoted the "epic fail" post realise the context and just not like jokes on HN, or did a couple of people choose to downvote, and then more people see what looked like a Reddit-esque joke that was being downvoted and just join in without understanding the point of the post?

As others pointed out, a similar mentality could explain the results on the Yelp page we are discussing, even if the entire thing was actually orchestrated by a competitor and/or triggered by a single unhappy customer where we don't know the full story.