It was around the 2016 election that things started to change. Before that, there was still a mentality of open and genuine discourse in most subs. But after the election that started to die, people started realizing bots and alt-righters had no interest in open discourse, on the contrary they would see to abuse such channels as a platform for their hate, and would use such hate and anger in an attempt to shape and suppress discussions. This forced the community to become far more jaded and less open, realizing just how vulnerable the community was to radicalization and firehouse misinformation.
On the early internet, we all had this vision that free access to information would free everyone, that unlimited information could only do good. Most of those people now understand how nieve we were, unlimited information means unlimited disinformation, and that organizations would always see to weaponize information the way they weaponize everything else. We are in a different internet age, now.