Body mechanics and proper progressions are esssential in any form of fitness and exercise programming. CrossFit has a number of workouts that include high risk exercises. Even when performed with good mechanics, things like tractor tire flipping and weighted lunges have a very high risk to reward ratio. That means, unless the exericise has a high probability of saving your life one day, the exercise isn’t a wise choice over another that has a lower ratio exercise with similar results. I also think that CrossFit often leads to a “I can top that” mentality. As with many other aggressive forms of exercise. There are some very good take aways in CrossFit. But always use sound judgement and adequate preparation and progressions.