They prescribe thought... which is a hindrance to truth and not a facilitator of it. They prescribe lazy reasoning.
Labels are always a function of ego. Labels say, "I belong to this clique, and I will defend the group... regardless of any specific situational circumstance" — which in effect, is a rejection of the independence of thought necessary for avoiding the sins of groupthink.
Labels are manipulations of human psyche. They should be rigorously investigated and generally resisted... or risk losing your Self to the sway of the crowd; and the crowd is often directed by the worst impulses of humanity.