The "toxic" metabolites aren't a sustainability problem though as long as the ecosystem forms closed cycles. Presumably it even helps biodiversity. Generally I

The "toxic" metabolites aren't a sustainability problem though as long as the ecosystem forms closed cycles. Presumably it even helps biodiversity. Generally I'd probably judge metabolism mostly based on power density and energy availability. How does anaerobic compare on that front? Though archaea tend to be anaerobic, and we should obviously all strive to be more like archaea, so maybe you have a point…