From my experience (anecdotal observation) is that with Crossfit what the participant brings into it largely determines what they take out of it. Now perhaps not all Crossfit boxes(gyms) share the same culture. But where I go there is a focus on form and scaling of workouts. Also those that are serious about progressing know how to hold back because rhabdo would destroy their(my) work and gains. Those who have no real goal except some loose idea of improved fitness and health never seem to push themselves hard enough to do damage. I'd say rhabdo would take a unique kind of desire to win over the pain to achieve.
Just to brag and promote: after a year of CF I've gained 6kg~ of muscle mass from 78kg to 84kg at 185cm. Crossfit is a tool to achieve fitness goals it doesn't provide the goals or the motivation just the means exercise both.
Here's an internal dialogue I just had.
Q: How do we test rationality skills?
A: We haven't come up with a comprehensive test yet.
Q: Maybe we can test some part of rationality?
A: Sure. For example, you could test resistance to akrasia by making two contestants do some simple chores every day. The one who fails first, loses.
Q: That seems like a pointless competition. If I'm feeling competitive, why would I ever skip the chores and lose?
A: Whoa, wait. If competitiveness can cure akrasia, that's pretty cool!
Now we just need to figure out how to make people more competitive in the areas they care about...