Take for example, a forum on ISIS. Yes, I've just triggered Godwin's law. I'm sorry about that.
Now, the idea is that there should be no challenge to ISIS on some parts of the Internet because they have the same right as anyone else.
However, this fails Karl Popper's criteria, don't tolerate the intolerant.
I support the criticism of any prejudiced and intolerant group in any forum (even the ones that Political Correctness blindly defends). If the goal of a group is truly noble, I will often support it.