Why do they say "there's no true Left in the US"?

A few years ago I would have agreed with this statement. But lately, I've seen a change described in several press articles and news pieces. The younger generations in the US demand true social justice and aren't afraid to say they're socialists, against capitalism or consumerism. It's a burgeoning revolution of course, since the establishment is still in control of traditional political parties. But this crack in the old broken system could bring about positive change in the long run. At least I hope so.