I really don't know why people comment if they don't know what's being discussed.
Reddit is essentially a hosting site for many (something like 150,000) different forums, which are called Subs. Each Sub is "owned" by a different person and has its own rules and own members, and its own culture.
There are Subs for knitting, for sharing photos of dogs wearing costumes, as well as Subs for deeply unpleasant things. There are Subs for every niche interest you can imagine, as well as hugely popular and mainstream Subs which are more like regular chat forums where you can discuss anything. When people make generalizations about the whole of Reddit I don't think they actually know what Reddit is.
A group of former MNers started a Sub there, ostensibly to discuss the problem that MN has with trolls and their complaints that MNHQ doesn't do enough to crack down on trolls. The sub is supposed to exist to root out trolls (like the pee troll, some of the fetish trolls who try to manipulate posters into sharing sexually graphic descriptions, or trolls who make up tragic circumstances so they can emotionally blackmail other posters into sending them money) so they can be reported and banned. Which is understandable, because MN does have a big problem with trolls.
However the Sub has since evolved away from outing trolls, and towards slagging off poster they don't like. S&B is a frequent target, and OP doesn't understand and is annoyed that the Sub is targeting S&B so much, when S&B is one of the friendliest parts of MN and doesn't really have much if any troll activity compared to AIBU and Chat.