>That a market reaches saturation usually means that the demand is met

A limit is a limit, doesn't matter if that's a demand limit, or a production limit, or a resource limit. The effect is still the same. Being under limits, makes things zero sum. If those limits were suddenly removed or increased temporarily, things would return to not being zero sum - at least until you hit another limit.

>It is rare that it means that not more can be produced.

In practicality sure. I'm sure we could make more basketballs than we do now. But physically speaking, you'd eventually hit limits. The earth is not infinite... we certainly could not make more basketballs than there is mass of earth itself. At which point we would either have to make new basketballs out of old basketballs, (zero sum), or raise our limits (mine matter out of other celestial bodies).

> Being under limits, makes things zero sum. If those limits were suddenly removed or increased temporarily, things would return to not being zero sum

Why do you think so?

> In practicality sure.

And that is what matters? Why is it interesting that there is a theoretical limit on how many basketballs that is possible to produce with the resources available on Earth when no conceivable situation exists when that limit ever becomes relevant?

I'm not sure under which rock you are living, but we are hitting limits fast. Soil degradation, climate change, acidification of the seas or phosphate ressources. Probably you'll die before these limits hit us hard(est). But eventually they will hit us and these are very conceivable situations...