Elica le Bon, an Iranian-American activist explains it well.
I remember when the leftists allied with Khomnei Islamist in 1979. And were promptly slaughtered when the Ayatollah took power.
I didn’t get it then. And I didn’t get it when I was in China in the late 1970s, when China’s Great Proletariat Cultural Revolution was still on.
But now I get it. And have done for some years. But many still don’t.
For them, Elica does good service.