That sound's like it's giving some kind of agency to the pathogen ;) when in fact it's more like: everyone that's severly infected isolates or dies, so the more harmless variants of the pathogen can replicate faster.
it's not "in fact" like you say; you merely provide an alternative way to understand what's going on and to describe it.
it's incorrect to claim that either is wrong because of the other.
in the end, we gotta learn to have multiple ways to explain the same things and it's best to shift between these 'theories' of what is going on as it serves our purposes. It's stupid to have this alternatives "fighting each other"; see? I just have agency to the ways to conceptualize, understand, and explain phenomena.