Because most people think that post-scarcity is largely a matter of technology. That is, once technology reaches a certain level, no matter how your society is set up beforehand the lack of scarcity will make all prior arrangements obsolete.

Of course, since we're not allowed to talk politics SFIA, we're not really allowed to discuss why a society that had the technological base for post-scarcity still wouldn't have it other than a vague 'evil authoritarian space government' kind of way.

So if that's your perspective, the explosive advances we've had with computer science, materials science, and fusion power in the past five years guarantees post-scarcity in a couple of decades if this pace continues.