Is swimming bad for you because there is a risk of drowning?
If you push somebody in a pool who has no idea how to swim, bad things happen.
Likewise, push somebody into a Crossfit gym who is ill-prepared and bad things happen. That gets amplified when you have unqualified coaches.
The definitive answer is that Crossfit can be bad for you at certain gyms under certain context and might otherwise be quite good for you at other gyms (especially if the alternative is doing nothing or training with bad habits), all depending on your current level of skill.
The danger in almost anything is associated with the context. In the context of Crossfit, if you are ill-prepared for the demands of Crossfit then it is most likely bad for you. If you're generally already quite fit (mobile/strong in particular), then Crossfit might be a great outlet for you to pursue.
Smart boxes will know how to adjust programming to suit your current level of ability, but few in my experience have great knowledge in this capacity still. If I had to guess I would say less than 20% of Crossfit gyms have adequate coaching, mostly due to the fact that their owners simply haven't had enough experience yet.
If you add really bad programming and stupid WOD's, and you often have a recipe for disaster.
Most people don't have the appropriate structure for things like olympic lifting, and that's why it's not as popular as other sports. The olympic lifts are very technical and you have to have to have the correct mobility and technique to do them effectively. Applying it to people who don't have that criteria in excessive volume or intensity often leads to bad things. If you can't get your arms above your head in perfect alignment, why are coaches loading that movement in the first place? Athletes can stick with simpler movements, or stay with lighter loads and get similar benefits out of their workouts.
If you can't get into the right positions first, laying strength over a faulty movement pattern is what often occurs, followed by injury eventually. The younger you are, and depending on your bodily structure, the more resistant you generally are to that, but it's only a matter of time. I spend a lot of my time as a coach, undoing bad movement, which takes a lot longer than just doing it right the first time.
The limiting factor with Crossfit is almost always in the coaching and what I generally view as generally bad high repetition programming (with exceptions of course). Most of Crossfit is skewed towards the WOD and most WOD's are energy system training at high volume and high intensity (meaning Crossfit is really skewed to conditioning as a base, when it should focus on good movement and strength), which can be applied together at the same time but should only be applied together infrequently and in calculated doses.
That's why we have this thing called 'practice' and 'training.' This same problem is rampant in youth athletics where kids spend way too much time competing and not nearly enough practicing and developing good skills that will aid them in future competitions.
It can be safe in the right box, with the right coach and the right program.