You've touched upon an incredibly grey area. Most forums will ban trolls, but therein lies the problem: define "troll".
I don't know what you said, where, and in what context... but I don't give benefit of doubt on this. Nor do I think you're guilty either... all I do know is that running a community is hard, and one of the things that the people of the community look to moderators to do is to keep the peace.
A difference of opinion can be minor, or major. And depending on the topic it can be quite offensive to some.
Have you considered that within a particular subreddit that the moderators were just trying to keep the peace? Has anything stopped you from starting your own subreddit to voice your opinion?
The below article was deleted from the queue in r/politics and I've been unable to post articles in politics and a few other subreddits ever since, using a particular handle from a particular IP.
My point stands: reddit has been complicit in silencing political opinion long before it began worrying about whether child porn should be allowed or not.
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.
Reddit and r/politics are not the same thing. Subreddits are user-created forums moderated as those creators see fit. Each subreddit chooses what it wants to see, how it wants to be moderated, and who will moderate. A particular sub community not welcoming you or your ideas is completely different from site-wide moderation.
I don't know what you said, where, and in what context... but I don't give benefit of doubt on this. Nor do I think you're guilty either... all I do know is that running a community is hard, and one of the things that the people of the community look to moderators to do is to keep the peace.
A difference of opinion can be minor, or major. And depending on the topic it can be quite offensive to some.
Have you considered that within a particular subreddit that the moderators were just trying to keep the peace? Has anything stopped you from starting your own subreddit to voice your opinion?