Control the language, control the debate.
Progressive was an alternative for Socialist. When both became tarnished the perfectly good “Liberal” was coopted.
When, after several decades, Liberal became tarnished there was a return to Progressive. But now Socialist is becoming increasingly acceptable again.
“Control the language, control the debate”.
Political Correctness was designed after the Russian Revolution to control the narrative.
Political correctness does not allow critical thinking or rational discourse. “Progressive” sounds appealing and nice to the fools.
It has worked beyond their wildest dreams.
I suppose they'll eventually recycle liberal but it will take a long time before the taint wears off.
For example, if a person tells me that he supports Bush or Trump (or anyone) because he is a conservative, I disregard the part about the conservative label because it is meaningless. I respond to the part about the candidate.
So, what difference does it make if Ted Bundy wanted to call himself a conservative and Charles Manson wanted to call himself an environmentalist? The labels aren't the real problem.