Even a very small step forward in evolution, taken as a 'short-cut', would result in failure. - life changed the chemistry around it - headline is the relative abundance and influence of free oxygen relative to CO2.

The point is that the search is ALWAYS for near neighbour variants, and even then, the huge majority of these are failures.

The (seemingly) vastly improbable success of variants that are not near neighbours has, I think, to do with complexity and the concomitant law of unintended (in this context, 'unwelcome' would be a better word, since no intention is involved) consequences. The larger the step, the exponentially larger probability of corollary catastrophic implications.