The idea is that it's not something that we can really choose to try or not. If/when we get to the stage where enough is produced to allow post-scarcity even in theory - i.e. the technology and the logistical science is there - it implies an extreme degree of automation. But if we have that, how would a traditional capitalist economy even work, if all that automation is concentrated in relatively few hands as it is now?

It works today because the owners of capital need workers to make that capital produce something useful, and even with all the economic rent fleeced from them, those workers still retain enough to then buy the products (if not their own, then that produced by somebody else). This enables money to cycle in the economy. But the more things are automated, the more people are unemployed, and - in capitalism - effectively excluded from the productive economy. So it's a question of how many people you can so exclude before the whole thing crumbles down.