> it's not up to you to decide they aren't the "real" left

Sorry, but sometimes it is. When Bolsonaro's crowd started caliming that the Nazi Party was a leftist party because it had "Socialit" in its name, I can comfortably decide that no, the National Socialist Party was not socialist. When my friends tell me that they are against socialized medical care and that people should also pay for their children's education, yet he says that he's a "leftist", I can comfortably decide that no, he's not.