Not sure if you're being glib, but this is a misunderstanding of both survival of the fittest and of nature.
Fitness is an environmental criteria - not one based on strength. A great example are small adorable dogs; they're certainly not the strongest or brightest, but because we share an environment and take care of them, they proliferate.
To say nature means for only strong individuals to survive is missing the depth of what "survival of the fittest" was meant to encompass.