Pseudonymity makes this possible. Users don't post selfies on Reddit, nor their names, nor do they friend people (though you can follow users). On FB users fear for their privacy, and users fear moralizers.
It makes me think that privacy is highly underestimated by Facebook. While it was once their key value proposition that real identity was desirable on a social site, with increasing political polarization and increased threats of government surveillance, the roles are now reversed and we'll continue to see privacy being treasured.
I have a Facebook account I NEVER post to and only check twice a week for about 30 seconds each instance. I do however spend an inordinate amount of time on Reddit. So much so that I deliberately have to wean myself off Reddit otherwise I'll waste too much time on it.
r/changemyview is one favorite example for excellent rational discourse on often very controversial topics.
Its a Trump hate thread with very little objectivity.
I've also run into subreddits run by very biased moderators who will mark any stories as spam they disagree or competes with their friends. And due to the shadowban system, many people never realize it.
That's why I stopped submitting comments and stories on reddit. I only browse it now.
In the subs I mod I have a long list of awful contributors on an auto-remove list executed by automoderator. I've got people who have been saying awful thing to people for years, but those posts are never seen. Banning them will only lead them to create a new account.
But I agree that aggregate comment vote is not an indicator of correctness - more of whatever way the wind is blowing at a particular time in a particular community.