Just an opinion from someone who has been around the internet for a long while. It wouldn't surprise me if most of the comments are bots. I remember what it was like to interact with humans, even dumb humans, and they aren't nearly as blatantly agenda-driven as commenters on what I'd call "visible social media".
There are plenty of people who have a vested interest in disrupting means of communication and organization and they are investing a great deal in "false idea proliferation".
My 0.02¢.
Oh, you asked for a percentage, in the popular subs? 80+%. In niche subs that don't affect the Overton Window? 5-30%. And yes, these numbers are favricated outward from my butt hole.