The forum I was speaking of is an extreme example of when the entire forum has been taken over by one side of the debate, and all voices of opposition are banned regularly.
What you describe is essentially when fanaticism takes hold. While we are used to that being constrained to religious venues, it can manifest just about anywhere. Look at the 9/11 Truthers or the Birthers to get an example of blind adherence to an opinion clouding one's judgement.
With that being said, EVC seems to go out of its way to be as accommodating as possible. I'm new to posting here, but I have been a lurker for some time. The main rules of conduct here are generally staying on topic and keeping the insults to a minimum.
Now if the EVC was dominated by Creationists, I would argue that you would no longer see the kind of discourse that exists here. Instead, it would eventually morph into a more dogmatic posting style where opposing (i.e. evolutionist viewpoints) would eventually be deleted and the posters banned.
A good frame of reference is Conservapedia, the 'counter' to Wikipedia. They heavily sensor the content and ban edits from those individuals who do not meet the status quo.
"Our future lies not in our dogmatic past, but in our enlightened present"