You pretty much nailed it with this comment:
But I would go as far as saying that the politically correct mafia on the left perpetuates a form of bigotry on its own because it alienates and “otherizes” those who do not share their ways of thinking and speaking about the world.
What you are talking about is Social Identity Theory. Prime examples can be found in politics.
* Party A will always be in opposition to Party B.
* When Party A imposes their morals they are saints. When Party B imposes their morals they are unfeeling bastards.
* If Party A is the majority Party they define compromise as Party B capitulating to their every whim.
* Party A, when in the minority, will always promote fiscal responsibility. When they become the majority Party all pretense to fiscal responsibility flies out the window.
* Party A will always defame Party B with every form of logical fallacy possible.
* Party A will tell you to not bother to research a member of Party A if there is a scandal around them.
* Party A will toss members of Party A under the bus to keep the Party going.
* Party B uses lies, damn lies, and statistics to prove their point. Party A tells the truth.
* Parties will always talk about improving the lives of the poor and middle class. Their enacted policies do the exact opposite.
* When members of Party B are accused of something, focus on their transgressions to divert members of Party A from seeing your transgressions.
* Guilt is relative. Party A is filled with saints. Members of Party B are nothing more than bullies.
* Morality is relative. It is moral when Party A does something but is immoral when Party B does it.
* If Party A announces their candidates early then Party B can spend time researching why the candidates for Party A are inept and craft a narrative for their base that proves their point.
* When an icon of Party A changes their minds on a favorite subject, the conversion from icon to pariah is instantaneous.
* Voters hate people who manipulate the political system for personal gain and profit unless they are a member of their political Party.
* Politicians are immune to their own hypocrisy.
* Free speech is great as long as we are the only Party doing it.
* Always defend your ground, no matter how stupid your position is.
* Silence the opposing views because our side is truth personified.
* Politicians, when faced with backlash from the few promises they delivered on, deny that it ever happened.
* Anybody who doesn’t think like Party A is an intolerant bigot. It’s really a shame that more parties can’t be more open and tolerant like we are.
* Parties will always say one thing and then do the complete opposite of what they claim to believe.
* If the minority party accuses the majority party of transgressions the majority party will assemble a team of “experts” composed entirely of members of the majority party and find themselves innocent. See also the movie Revenge of the Nerds:
You see, instead, I am going to organize… a special, blue-ribbon fact-finding commission… made up of myself and, uh, Miss Betty Childs, and we will get to the bottom of this dastardly deed. — Stan Gable in Revenge of the Nerds