That's very very true. However, none of the current Left is.

I never said they did.

You very heavily implied it, though.

But they demonstrate that we can't just assume that people aren't antisemitic just because they are left(-leaning)

Sure. Just like we can't assume that people from Nepal don't pollute. It's not the norm or even something of heightened risk compared to other demographics.

Unless of course you don't want to learn from history.

That's rich coming from someone trying his best to leap to illogical conclusions based on two events that are specifically remarkable for being atypical.

If the argument that being antisemitic precludes you from being a leftist, that's not a fallacy. If you don't abide by a set of beliefs, then you are not a follower of those beliefs.

I'm not a Scotsman because I'm not from Scotland.

Similarly, I don't think most libertarians are true libertarians because they don't care about liberties except their own. And if that's the definition of libertarian, then everyone is a libertarian.

"No true leftist is antisemitic."

A strawman inventing a no true Scotsman? That's impressively fallacious 😄

I didn't and indeed have never claimed that there aren't any antisemites on the Left. Unfortunately, a lot of people on the Left are starting from the point of "the country (incorrectly) claiming to be representative of all Jewdom has been committing unspeakable atrocities for a century" and being misled from there down rabbit holes that sometimes go all the way to ACTUALLY antisemitic conspiracy theory nonsense.

That being said, those people are a tiny minority, and your two examples from the days of disco and earlier don't prove otherwise.