I don't think it is just Macrumors. I remember being part of Slashdot and a handful of other forums over the last 10+ years... Sure people disagreed and had discussions that didn't always result in seeing eye to eye but I'm seeing that people today just don't have tolerance for difference of opinion today.
There are more "trolls" that post to drum up responses ... a reaction. People enjoy being unreasonable to set others off more than ever before. Close minded posts about how things should be vs using forums to discover other people's opinions is far more rampant now.
I left Facebook in 2016 because of the fact that FB seemed to encourage outrage and discord. People in general are attracted to that and platforms make a lot of $ off the reaction so they naturally encouraged/boost such posts.
I definitely see why some of the subforms that
@eyoungren talk about still have that old MR vibe and are be REALLY enjoyable places. ---- I find myself less interested in news threads, however I believe MR makes the most $ from them.