OOC chatter isn't the issue, its when it spirals off into a variety of topics that lead to ill-will among players.
That issue can be the fear that players are allowed to make power builds solely to kill anyone they feel like killing.
The issue can be attacking someones political or social values directly, or just in their presence.
The issue can be having no place to go where you can deal with OOC things, without an OOC Quiet Room.
The issue can be discussing a disliked play style and creating a hostile environment.