I suspect this is why "post-scarcity" is generally used to describe a state of affairs that does not currently exist, such as the idyllic Federation in Star Trek. In this context it was used to describe a society fundamentally different in significant ways from any past or present human one.

I don't know if I agree that post-scarcity cannot exist. I know that imagining a way to get there is very challenging. Knowing that scarcity is real certainly informs my politics, though.