how they hurt in 2012 https://news.ycombinator.com/item?id=4926615
and 2011 https://news.ycombinator.com/item?id=2279260
Smaller threads:
2014 https://news.ycombinator.com/item?id=7311078
2011 https://news.ycombinator.com/item?id=2283113