My hypothesis as for why that's the case is that the upvote system encourages people to construct the wittiest, least-substantial comments they can in order to farm the largest number of instinctual upvotes as possible. What makes this even worse is the fact that heavily-downvoted comments on posts are hidden, so there's an actual incentive beyond "le internet points" to appeal to the greatest number of people possible. Doing otherwise is sabotaging your ability to engage in conversation on the platform.