The current solution upvote system slightly rewards shorter code over efficient code on many problems. I think this might change in the future if they decide to show the average runtime of each solution.

+5Kyu kata check for efficiency more often as a requirement to pass the tests. On lower level kata, you can mostly expect short solutions that are far from being considered best practices.

Other reason for writing shorter code is simply having a little bit of fun. I've done it myself.

So, why are people here focusing on less code lines instead of perfect run times? Sorting is not a reasonable solution if efficiency is required.