Um, wtf? That doesnt describe Tera at all. Someone is smoking something over at IGN. Tera does use channels to some degree but there are players in all the channels. Players are all over the place. I think there might be a few dungeons that are instanced but any instancing is a small part of the game. World bosses, world pvp etc exist.
EDIT: found the origin of that post; its from some clown who posted a reply, not an official or employee of IGN. So basically ignorant banter of postcount+