Stated harm is vastly overblown. Your average /pol/ack is too unmotivated to ever leave the house or even have an in person social interaction with a non-family member. It's a gathering place for the NEETs and hikkikomori of society. It's too unwelcoming to anyone with a functioning mental state and their activities live and die within that board.

You can't just peer into their world and judge them by the same standards as normal society.

If the mere existence of a place where people voice highly disagreeable opinions is an existential threat to you, then I think that says more about you.