Definitely, I agree. But I also think people tend to oversimplify the argument that stronger = better athletic performance. No one is saying that it's a substitute for technique or sports-specific skill. In fact, that should be pretty obvious. If I say someone is a great runner -- both sprinter and long distance -- it's obvious to everyone that that doesn't mean he is a good soccer player. But that doesn't change the fact that speed is an advantage on the soccer field.
The strength argument is similar. Though the degree to which strength is an advantage, and the point at which diminishing returns set in, will vary based on the sport in question.
For a sport like Crossfit that actually involves lifting weights (including bodyweight), I'd think the diminishing returns set in relatively late. If I take a look at the recent Crossfit WODs, I know which ones I would be pretty good at and which ones would kick my ass just based on the movements and poundages.
5 rounds for time of:
225-lb. back squats, 10 reps
275-lb. deadlifts, 10 reps
Rest 2 minutes
This is one I'd be pretty good at, even though I don't train for crossfit at all. Obviously, the stronger your squat and deadlift, the easier this event is. The OP w/ a squat of 310 is going to be at a huge disadvantage competing against a guy with a squat of 500.
This one, on the other hand, I know would totally kick my ass:
21 one-legged squats with a 65-lb. dumbbell
185-lb. clean and jerks, 15 reps
Rest 15 minutes
Then, for time:
21 parallette handstand push-ups
165-lb. snatches, 15 reps