It's that, but also the fact that many subreddits are often controlled by powermods with tons of subreddits they control. They often also end up leaning very he

It's that, but also the fact that many subreddits are often controlled by powermods with tons of subreddits they control. They often also end up leaning very heavy towards the radical left. This ends up further compounding the echo chamber problem, especially across the "default subreddits". /r/politics is a good example of this. It is very hard to have any view that is classically liberal or conservative on a good chunk of reddit. These views typically get removed by moderators, get you banned in subreddits, or they get the result you speak of where others try and downvoted them and tell them how bad of a person they are.