I think it was the Italian Communist Party that put out a statement once that said, "We are not leftists. We are Communists, and proud of the fact."
The use of the term "leftist" for self-identification might as well be an admission of failure. Ideological, intellectual, educational, dialectical failure. For all that we mock our "Marxist-Leninist-Maoist-Gonzaloist with Trotskyist-Bukharinite tendencies" overtitling nonsense, at least that mistake comes from a place of trying very hard to be informed and coherent. "Leftist" is a term we use for other people - its only real use is when we need a catch-all for a large group of people with disparate tendencies. If you use it to label yourself you're just telling me you're not rigorous, or not well-read, or both.