Trans people on reddit would often get downvoted to oblivion for seemingly no reason. It happened to me on occasion, with comments that were otherwise benign, non-controversial and at least tangentially on-topic. Like fair enough if they stayed at 1 but these would be at -5 or lower. And always on posts in default/major subreddits too. This stuff was done systematically to silence trans users by having their comments hidden from low vote total. Because actually posting hateful comments would just get reported and removed in those large spaces, and this goes undetected.

Now imagine a trans Instance like Blahaj, dealing with the potential of a new instance showing up just to downvote members, and that happening, over and over. No comments, just downvotes. That's why Blahaj has them disabled.