I don't have the stats to back this up but I imagine there would be a significant portion of unsavory comments that appear from people/bots that didn't actually

I don't have the stats to back this up but I imagine there would be a significant portion of unsavory comments that appear from people/bots that didn't actually watch a large portion of the video. I think it would work in YouTube's and creator's favor to disable adding a comment until you watch a large portion of the video or you load all the ads.