many (if not most) countries are - political divisions which have historically been formed around a discrete and cohesive people that share common culture, language, and history.

This. Is. A. Myth. I would suggest you look at this classic statement on the mythological origins of the modern nation state.

ia601200.us.archive.org - Benedict Anderson

You might not like that. You might not like the fact that humans tend to organize themselves around conceptions of a "people," rather than a multi-ethnic multi-cultural amalgamation that ignores nearly all aspects of personal identity and instead is based solely on physical proximity and geography. That individuals tend to draw meaning and importance from their participation and membership in a specific group, rather than undifferentiated "humanness." But that's the way most people are. That's how most countries are.

This has nothing to do with what I am suggesting about the "nation state". I'm pretty sure you haven't heard a word of what I have been saying.

Being anti-Zionist is to say, "but not the Jews."

It is not what I am saying. I am saying that all ethno-nationalist "projects", with Zionism being the ethno-nationist project of some Jewish nationalists, is premised on the political construction of a state based on an imagined community of "people". This project, in which civil rights and citizenship is limited to "the nation", is a racist project. Worse than that, it frequently leads to ethnocide, ethnic cleansing, and genocide. The Zionist project is itself a product of various nineteenth century European projects that didn't know what to do with Jewish minorities. The problems of inclusion and exclusion in any state building project centered on an imagined community of homogeneous people is that "us" can never be clearly and definitively achieved. Even today the state of Israel is engaged in heated battles of who is really a Jew worthy of citizenship.

You're not decrying the dissolution of Czechoslovakia as a "racist state building project,"

I spent a good part of my youth involved in activism against the racist state building project of white South Africans. I was arrested for that activism. While not active politically in opposing these, I would point to Rwanda, Myanmar, and our own American history as catastrophic nation building projects. None of these had to happen this way. Canada, while not perfect, has pursued a more admirable path toward nation building.

The problem with Zionism isn't that it's a Jewish state project. The problem is that it is, at this moment, a genocidal state building project. This is the almost inevitable result of any nation building project.