It has been self-only since 3.0, but they are giving it a stacking debuff of 1% crit just like imp scorch (where imp scorch will decrease to 1% from 10%, same with winters chill and others). And afaik they will not stack, so expect everyone's crit rating to be 5% lower come Ulduar. I guess that is one way that they can make sure people have gear progression without having to reach diminishing returns on crit and so forth.