To understand Zig Forums you first have to understand the Left and Jewish subversion in its totality.
Principle 1: The Jew does not actually desire a Communist revolution as Marx or even (in a rare case of a Jew acting genuinely) as Lenin envisioned. Jews want a quasi-revolution that empowers THEM at the expense of the Sassenachim, hence their reliance on urbanite bureacrats, vanguards made up of intellectuals, criminals and low-level state officials, etc.
Actual peasant uprisings historically have ALWAYS resulted in Jews being exterminated, particularly in Eastern Europe–I'm sure you're familiar with the Khmelnytsky Uprising, where Cossacks and others essentially rose up against their Polish masters not so much because the Poles were Catholic and oppressing them, but specifically because they employed Jews as landlords and administrators who ruthlessly exploited Ukraine and the Cossacks. Jews do not want organic revolts but controlled revolts–i.e., they don't want ACTUAL left-wing revolutions, they want systemic transfers of power to Jews or Jewish agents which they can *call* revolutions.
Principle 2: As a result of Principle 1, the Jews must ensure that any revolutionary movement is controlled by Jews, or else to ineffectual to actually instigate and win a rebellion against the current social order without Jewish assistance. The greatest weapon in the arsenal of the Jew is Intersectionality, and it has been employed to GREAT effect in every field, but especially against Left-Wing movements in general. Part of the reason why Jews are primarily associated with the Left is that Intersectionality, or Identity Politics, makes it very easy for those movements to control.
Conclusion: Because of Principles 1 and 2, any Left-Wing group that is not currently infested by trannies, niggers, various shitskins, faggots etc, is targeted for mass-inclusion of those peoples because this is the only way that Jews can break up and control them or render them inert. If a left-wing group were actually made up of white men, it might succeed–this is totally intolerable to the Jew, so he finds ways to sabotage these groups by forcing these marginalized mentally ill people into them at every opportunity.
A side-note: This is also what happened to Lolbertarianism, Atheism (remember Atheism+?) and most recently the "Skeptic" community, and it is what happened to the "Alt-Right" as well. Jews will actively seek to sneak faggots, blacks, Jews, Jew-Enabling Sassenachim and other corrosive elements into any movement, because the very EXISTENCE of diversity grants Jews power within that movement.
TL;DR, Jews sabotaged the Left hard, and Zig Forums is the perfect example of what an ineffectual, weak, and cultureless political group looks like. Halfchan's Zig Forums has also been subverted ruthlessly in this manner. This is why ZERO tolerance is important. ZERO compromise. Any crack no matter how small can and will be exploited to turn your movement or space of conversation into an ineffectual cringe-arena.