I think it's an important, and relevant, distinction.

If Steemit were actually a ponzi scheme (it paid out old investors from fresh cash from new investors from a centralized point of failure), then failure is an inevitable result. Eventually, you run out of "greater fools".

Since Steemit is given value based on market demand, it's not inevitable that it fails, any more than a multitude of other products produced in some kind of limited capacity that people want.