A Jewish woman I know mentioned to me recently that Hitler’s justification for annihilating the Jews included the claim that no one remembered the annihilation of the Armenians (by the Turks). I had never heard of this statement before and was intrigued, but it turns out that he said it in a speech to his generals about annihilating the Poles, plus there is some doubt whether he actually said it (see here). Still, even if not genuine, it was attributed to him as far back as 1942, and so represents the situation of the world at that time, namely that the massacre of Armenians by the Turks in World War I had been forgotten or was at least seldom talked about.
I am saying the same thing about the left with respect to the massacre of leftists in Iran by the Muslims that began in 1979. I almost never see it mentioned, and when I do, it is more likely to be mentioned by non-leftists than by leftists. But if leftists themselves cannot even remember this event, then no one should care if leftists get massacred again, especially if they are massacred by Muslims, who carried out the first massacre. After all, presumably the Armenians still remembered the massacre in the 1940s; it was just that other people didn’t. Why even join a movement that doesn’t care if its own members get massacred?