Well, it’s a rather convenient shorthand to describe the set of views and positions (largely emotive and inconsistent) that characterize leftist thinking.
But that's a large part of the problem, reducing everything to a simplistic "left-vs-right" dichotomy – everything is either "left" or "right", and everyone who is good/sane/rational/decent/etc belongs to one of them and everyone who belongs to the other is irrational/insane/wicked/etc
Yeah, IMO "left" and "right" are just two different flavors of neo-liberalism factioned off like sports teams; and the mentality and self-awareness of those who back either one tend to be similar in nature to the point of being indistinguishable.
If someone is pro-war (to any degree), anti-worker/union or pro-capitalism I have a hard time taking them serious as a leftist; that's more of a liberal bag.
But that's a large part of the problem, reducing everything to a simplistic "left-vs-right" dichotomy – everything is either "left" or "right", and everyone who is good/sane/rational/decent/etc belongs to one of them and everyone who belongs to the other is irrational/insane/wicked/etc