Originally Posted by
Nockian
Because we aren't dealing with a pure machine, but a specific entity, with a specific identity and of a specific nature. Our adaption to the environment is only partially physiological, but mostly through the mechanism of adapting our environment through use of our mind. In effect you are questioning an axiomatic fact.
The physiological component has already been answered as an observer fact there is a law of diminishing returns on strength. This is the science.
We are using our minds to figure out how to make us stronger than we would normally be for whatever activity we are performing, but the nature of our physiology is finite, if it were not, then nothing in the universe would have any identity and therefore there could be no existence. We cannot get infinitely stronger. This is the philosophical component.