In general we're terrible at hiring. We overvalue raw intelligence and specific technical knowledge. (Sorry, this project uses Ruby 2.5.1 and you only know Ruby 2.5.0.)
Meanwhile we undervalue the most important skills: judgement, empathy, and communication. I don't care how brilliant my colleague's code is if the person can't explain it, is a jerk, or the code never should have been written in the first place.