Earlier quoted context omitted.
The only thing this tells me is you have an error in your hiring process that is leading you to interviewing people in person that cannot do the job. This should never happen.
Nope, hiring processes should bias for type 1 (false positive) errors at ingress, and bias for type 2 (false negative) on the decision side. Otherwise we miss interviewing people who can do the job, and in my experience, some of the most interesting people; but this means, one may sometimes be interviewing people that cannot do the job. Since these are human-mediated processes, there is no accurate single-stage filte…
I'm not saying no human should be involved. I'm saying an excellent human should screen candidates in a phone (or Teams or Zoom or whatever) interview before they are invited to sit across from you at your desk or in a conference room.
If you find yourself sitting across from someone who cannot technically do the job, your step one has failed (and should never fail).
If you don't hire someone because their in-person interview didn't go well, it is social skill (or cultural fit) related.
If that's not the case, reference step one to see that you have an error in who you are inviting for in-person interviews (or your phone screener should not be the person phone screening).