I don't get the (perennial) dichotomy.

It seems to me the question of whether a submarine can swim is well-formed and relevant.

I feel confident that no advanced propeller driven craft will ever develop flippers and fish-like swimming as an emergent phenomenon.

I also feel confident that an artificial device that does swim like a fish is entirely within the realm of engineering, let alone science.

It has never made any sense to me that, by analogy, there is a conflict between those two beliefs.

Economic forces may preclude fish-machines, but it might just mean they will be delayed for a long time because they are difficult.