Ask yourself why they would want to separate the left

Oh, i’m sorry, zionists are leftists now?

Zionism is a settler-colonial ideology which its goal is establishing the state of Israel on the Palestinian’s occupied land.

“If I were an Arab leader I would never make terms with Israel. That is natural: we have taken their country. Sure, God promised it to us, but what does that matter to them? […] They only see one thing: we have come here and stolen their country. Why should they accept that?” — David Ben-Gurion

“You are being invited to help make history. It doesn’t involve Africa, but a piece of Asia Minor; not Englishmen but Jews… How, then, do I happen to turn to you since this is an out-of-the-way matter for you? How indeed? Because it is something colonial.” — Theodore Herzl draft to Cecil Rhodes

Zionism (the belief that Israel has a right to exist) is fundamentally incompatible with leftism. Fighting with zionists isn’t left-wing infighting, it’s punching right.

and who benefits from that.

Leftists do. movements do not need zionist liberals muddying and diluting it until it’s meaningless.