[zepto]

> The phrase "leftist" properly applies to a group of people who essentially haven't existed in the United States.

There are large numbers of people who describe themselves today as leftists, and there have been for the past 80 years. People across the political spectrum, academics, and the news media use the term in relation to contemporary politics.

If you are using a definition that stopped being relevant 80 years ago, it will be hard for you to have a coherent discussion with people today.