I think your thinking is flawed. I believe most elite athletes push themselves to their genetic potential limits. If anything goes slightly wrong when you are redlined, you have a greater potential to get injured. If you take an average person who goes beyond their current physical limits, their body can handle it. For the most part, their ligaments, tendons, etc. can handle it. For an elite athlete, their isn't as much of a safety factor.
I can certainly see the flaws in thinking injury may be necessary or beneficial!
I agree with what you said. Makes sense. Higher performance means less room for error. I really like car analogies so it could be like a commute to work versus racing on a track. Driving to work, you can get away with taking your eyes off the road, day dreaming, even eating or talking on the phone (yes you're not supposed to be but most do anyway). However, if racing on a track at high speed you can't afford to eat your lunch whilst talking to your friend on the phone.
I would genuinely like to think injury wasn't essential.
My strongest female client has never really been injured yet she is highly motivated, very determined. Well, she had some shoulder pain when I started training her but at that time she was a class fanatic (spin, circuits, boxing, etc - all of them) and didn't do any lifting or train for anything in particular. Cardio freak, basically. I've just made her a training partner, too. I'm in control of her training and like to think she will never get injured as a result of poor programming or technique. I should never say never, obviously.