There's been talk of doing this throughout the years and it's never panned out. Simply put, downvoting is the best way of making sure the best comments stay on top and the worst stay near the bottom. Of course people are going to use it to go after their opponents, just like they would with any other feature. What I usually do and what I recommend other users to do is if you have polite disagreement, upvoting each other shows even though you may disagree, you still respect the other's opinion. Of course if you get some user being like "fuk yu, my politician is the gr8est yurz is like literally Hitlur", that doesn't really deserve an upvote. I went ahead and upvoted your comments on the image you linked.