Up till now the physical distinction was not important. Humanity was coming up with new ever more effective energy sources and ways to "produce" them.

But now things change. If we talk in pure physics terms, what does the Second Law of Thermodynamics imply? Sure, it talks about zero energy throughput directly - but apparently a fixed finite value allows just limited valuable effects. Regardless of what money we may come up with. In other words:

There can be no perpetum mobile of a monetary (or social) kind!.