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.