The behavior you're describing (not being able to submit from a certain user account from a certain IP) is a result of reddit's quite sketchy spam filtering mechanism. Unless you have been notified that you've been banned from a certain community, your posts are simply being absorbed by the spam filter.
You have also mistaken the views and actions of a specific community for the views and actions of the site owners. Anyone (yes, even you) can go start a subreddit whenever they want, and restrict content however they want, even if that includes suppressing information they don't agree with or banning users with whom they disagree. The idea behind reddit is that people show their support for a specific community by frequenting and contributing to it. If you don't agree with the way a community is being run, you are free to find a better one or even to start your own.
I think you're missing the point of the users who see this new rule as a negative mark against reddit. The admins have always been supportive of allowing any content that is legal, even up to a very specific definition, which is why these now removed subreddits were allowed to exist for so long. Lots of people are making the slippery slope argument, saying things along the lines of "how long before they ban /r/trees?", which is a marijuana-based subreddit. In response, the community organizer, hueypriest, said this:
>They'll ban /r/trees when they pry it out of our cold dead hands.
You can imagine why it might be frustrating to people who would expect them to approach all content with as much vigor as they do in the defense of /r/trees.
The way I understand it, and the way it has been explained by the admins, is that policing the kind of content that is now not allowed had taken up a significant amount of their resources, and it was becoming unsustainable. However, a lot of users clearly see this as a sign that the admins are backing down as a result of legal pressure and also for the purpose of preserving the image of the community.
For users of old, this is a rather new phenomenon, and it is somewhat offputting. If it was solely a question of sustainability (how much time are they wasting policing the content?), that would probably be acceptable, but it's difficult to believe that it is the sole reason for the rule.
Is this a joke?