I have no recollection of that and I’ve been here for a long time. Are you sure you aren’t just confused by the fact that not all liberals considered themselves progressives? I fell into that camp back then.
The issue here is that you’re assuming people we’re hiding their true beliefs vs the reality that people’s political opinions can change and also there are new, younger, people becoming political active. Millennials in general are further left than Gen X’ers since the latter population came of age partially during the cold war.
That’s good as a Democrat I don’t want Communists in the party. But, I won’t tell them not to vote Democratic, just like you (collective) won’t tell white supremists not to vote for Trump.
Communists don’t even like the Democratic party… like many others on the left that aren’t Democrats they’ll vote D because its closer to their values than R.