Anyone who has honestly reflected on what they know about hiring, will tell you that no matter how locked-down you think you have it, you dont. There is still way too much left to chance and way too much that you just dont know. To avoid this, companies that care about preserving their culture will sometimes adopt a “default deny” approach. It’s ok to miss a potentially good hire rather than to take on a bad one. This isn’t silly geek risk aversion.. It’s because one bad hire can do amazing damage to a culture (an area bad hires can be amazingly productive in).