"At the time, we were actually racing another company in our Y Combinator batch. It was called Simply Insured. Originally it was fairly different from us, but about halfway through YC the founders decided that they wanted to do what we were doing, and the company pivoted into our market."
One of the more interesting parts of the article. Not sure how you prevent or discourage that.
Zenefits is pretty awful. A startup I was advising was using them and they were ridiculously slow to respond, failed to make sure payments were processed appropriately causing their insurance to lapse, screwed up payroll taxes, continued paying someone who had quit, and basically failed at every task they were supposed to be helping with. Further they had no personal accountability and did everything they could to shuffle blame rather than just trying to resolve the issues.