Geopolitical power comes mainly from 3 things, resources, technology, and controlling your “excess” (i.e. the people that do the “worst” work) population. Historically borders have been an effective means to more-or-less control all 3.
Controlling your own borders is really childs play, controlling other people’s borders is where the fun really starts. Sykes-Picot for example ensured that the Middle East would fight over resources (water, arable land) and who the “excess” population should be by drawing borders in creative ways preventing the reformation of the Ottoman Empire after its defeat.
I mean at this raw of an argument you might as well argue for Lysenkoism because unlike Darwinism/Mendelian selection it doesn’t “put things in boxes”. In practice things are put in boxes all the time, it’s how most systems work. The reality is that as communists we need to mediate the negative effects of the fact that things are in boxes, not ignore the reality that things are in boxes.
The failure of capitalism is the fact that it’s systems of meaning making converge into the arbitrage of things in boxes. At the end of the day this is actually the most difficult part of building communism, the Soviet Union throughout it’s history still fell ill with the “things in boxes” disease. It’s how you get addicted to slave labor, it’s how you make political missteps because it’s so easy to put people in a “kulak” in a box that doesn’t even mean anything anymore, it’s how you start disagreements with other communist nations because you really insist that they should put certain things into a certain box.