Because it is trolling. HN is reading, upvoting, and commenting on an economics essay by someone who studied "Fine Arts" at the "School of Visual Arts" in NY and now works at "CYCLE Interactive" as a designer. The author hand waves about the 80/20 rule as if discussing things using their own common sense is equivalent to mathematical rigor or scientific evidence. It's simply a link-bait headline that evokes a response from a large portion of the users on HN.
Honestly, it's disturbing how many red flags there are in this article and yet it makes the front page of HN.
Everyone's half-baked opinion is not equal. The way I feel every time I watch a movie where a machine spontaneously "comes alive", and then have to listen to people talk about "what if it really happened", must be similar to how economists feel every day. No wonder it's the dismal science.