Unfortunately I think it's a combination of popularity and exposing what happens in upvoted systems as opposed to discussion forums; the lowest common denominator rules.

"Both sides" fallacies, typically having a political meaning, are naturally going to get exploited on social media sites where both sides upvote the poorly baked, emotionally charged fallacies.

It is alarming to me as a statnerd that the NBA and NFL communities seem to be getting dumber as time goes on, not smarter, but I'm not positive this is a Reddit problem (but possibly, due to how mainstream it is now).