Let me preface this by saying that I absolutely despise LeftKKKoms, but I think it's important to hate them accurately. They're using "progressive" in the Marxist sense, meaning "progressing toward Communism." The thing is, even by that standard, it's obviously true. Is a German "working class" that enjoys the benefits of slave labor or one that has to live without going to be more inclined toward revolution? The answer is obvious, and you can see it play out all across the Global North today, for example in the popularity of "Left Communism."