There's no law of physics problem here. You could (with a benevolent global dictator) have everybody happily living with a constant amount of food, heat, clothes, etc., and still have an increasing standard of living by increasing the amount of non-material production. Unless you are stuck in the model that studies only the material production of goods as a true "economy."

Alternatively, using another model, the plague is relevant because you can have a constant growth scenario for centuries with a large reset every once in a while. The Roman Empire gave way to the dark ages. The middle ages gave way to the plague. Perhaps we're due for a reset.

That's not to say that it's particularly pleasant to live when the collapse is taking place!