Reddit has subreddits on the right and left that will ban you for disagreeing, or even for having made a comment in a subreddit they don't like. That was theoretically always possible, but at some point people decided such a policy was a good idea.
I personally think a misstep of reddit's has been relying so much on volunteer moderators. Why are people willing to put in so many unpaid hours of labor? Apparently, the answer is sometimes because they have a political cause they want to promote.