To be fair it is environment dependent more than anything else. Forget competence, charisma, intelligence, and everything else about the candidate that could bias their selection and instead look at processes and code already in place the new candidate is jumping into. Does the environment strongly favor original ideas/solutions or does it dictate the narrow acceptance in the most narrow of boundaries?
I have been on both ends of this as well. It is common in software for shops to define success in extraordinarily shallow terms such as whether you are using spaces versus tabs and indenting properly. Another example I experienced last year is whether you should write a giant monster configuration or a small function that receives a single argument. The reasons why shops coat themselves in blankets of code style and configuration is because they typically don't trust their developers and instead strive for a normalized baseline. They are looking for wonderful solutions, but rather task completion.
The lack of conformance isn't necessarily an indication of lower capability, but it is an indication of incompatibility. Competence and conformance are wildly out of sync when the candidate is misjudged relative to the work available. That is completely an assignment failure opposed to a candidate failure. Having gone through this myself it has taught me to ask very probing questions, as a candidate, during the interview. If, as a senior, I can determine I will not be a good fit I will happily disqualify myself.
> A coach like Bill Belichick might have a fantastic, detailed answer demonstrating a thorough understanding of every aspect of football past and present, but he could never make the throw himself.
Would you really hire a coach to be your quarterback? Is that a thought you would really entertain? Even if that coach could do that job he/she would be more valuable doing other work. I would consider this a solid example of interviewer/assignment failure.