> The overwhelming majority of mutations end up being harmful or neutral. An exceedingly small fraction are beneficial.

Neutral drift is perhaps the most important part of evolution. It's how you preserve diversity over time and avoid getting stuck in holes in the fitness landscape.

If we only ever made steps that improved performance we'd inevitably see premature convergence. The neutral drift can overpower progress toward a global minimum, but it's a lot better to be going in circles than to not be moving at all. Diversity collapse is the worst thing that can happen to an evolutionary algorithm. You must reject superior solutions with some probability in order to make it to the next step. You can always change your selection pressure. You can't fix information that doesn't exist anymore.