It's a fantastic ideology; arguably perfect. Unfortunately, it has never worked and will never work because it is incompatible with human nature. The more humans involved, the more extreme the incompatibility.
does anyone using the "human nature" argument even know what they're saying?
what about "human nature" or "humans aren't perfect" undermines socialism or communism? by what mechanism?
it feels like it's a talking point that means absolutely nothing when viewed critically, and is only mindlessly repeated because it sounds cynical and "smart"