Yeah, see below, but most people won't even be able to get low enough on one leg to do too much damage. It's like doing the full splits- sure, if some couch jockey tried it they'd tear their groin, fortunately their body won't let them get that low in the first place. Or how an untrained person would get crushed by trying to bench 400lbs, fortunately they couldn't lift it enough to crush themselves. I've yet to see an out of shape person get all the way down in a pistol squat (let alone going back up too).
Is their a safer, entry level way to do these where you can work on your balance/weight distribution while at the same time not fucking up your knees? It just seems easy to make a minor mistake that puts way too much stress on the knee joint....I tried a few of these and my knees are relatively strong and healthy, but as a big&tall guy I still feel that if I was off just a bit here or there, a spill/injury could result.