They passed on hiring someone who suggested "sharding" in a chalk talk as a way to potentially scale a database because they wanted an answer like "add an index

They passed on hiring someone who suggested "sharding" in a chalk talk as a way to potentially scale a database because they wanted an answer like "add an index"??? This AFTER already interviewing them twice, AND liking them, AND learning from them, AND recognizing their potential? This is why asking "I'm smarter than you" questions is stupid in interviews. This is a fail for them not the candidate. Do not follow this pattern or advice. If you have a great candidate, that fits your organization, teaches you something in their interview, and clear has potential... You hire them!