I should have been more specific, my bad. I've been thinking in my head about strength per se, not muscular endurance or explosiveness. I think that those examples build endurance, but not so much strength.

look at pictures of olympic athletes, notice who's ripped

I think that in a lot of sports, you don't build much strength (per se) by participating in the sport, but you need strength to be good at it, and so competitive athletes lift weights.