I believe the original intention of the leetcode interview is to let the employer gauge the thought processes, communication style, and problem solving approach of the candidate, more so than strictly the candidate's ability to get the absolute hyperoptimal solution.

But it has been corrupted. Demonstrating your thought processes, communication style, and problem solving approach is still a factor. But being able to quickly get the hyperoptimal solution in 20 minutes usually trumps everything else and often becomes the single make-or-break factor.