It works like this. Most of the time most editors are polite, but sometimes you get frustrated and are not. You might not write "fuck you fucking nazi-lover!" or something extreme, but something like "your opinion is idiotic!" or "you don't know what you're talking about here..." It happens everyone. However, if you don't agree with the "consensus" every little outburst will cost you much more. A newbie will be banned for much smaller infractions than a regular.
So, if you are having an argument with someone who is a "respectable editor" or "valuable contributor" in the community, they can and will be quite rude to you but you must not pay back in kind because you will be banned.
There are also intricate rules governing "reverting". Reverting means you are undoing someones changes and I can say from experience that having your edits reverted can be frustrating. I don't know exactly what the rules are but they seem to be effectively that the more "respectable" you are, the more you can revert your opponents edits.
This power imbalance can be seen all over Wikipedia if you look for it. Many articles have editors that consider themselves the "owner" of that article. The way they have written the article is the best way and they don't see their own NPOV violations (Wikipedia term for writing biased texts). Sometimes the talk pages and their archives contain dozens of comments from anonymous ip users raising issues with the article and they are all refuted by the owner. They don't have the endurance or enough standing in the Wikipedia community to fight so they give up and find more constructive things to spend their time on.