You're not wrong. Communism implemented perfectly would also work beautifully. It just can't.
The main difference here is that Scrum is not nearly as complicated to implement. Though the issue is the same. There's always someone somewhere who thinks the process doesn't apply to them and the whole thing falls apart.
I did work in one company that had a fairly well implemented Scrum, and it did work pretty well. I've never seen it replicated though, so for all practical purpose, it's exactly as you say: it's not worth trying because it only works when done perfectly, and that almost never happen.
The main difference here is that Scrum is not nearly as complicated to implement. Though the issue is the same. There's always someone somewhere who thinks the process doesn't apply to them and the whole thing falls apart.
I did work in one company that had a fairly well implemented Scrum, and it did work pretty well. I've never seen it replicated though, so for all practical purpose, it's exactly as you say: it's not worth trying because it only works when done perfectly, and that almost never happen.