I was a college athlete in a large program where we used Olympic lifting extensively. It's true that form was emphasized over weight and repetition, and I gained quite a bit of muscle mass from that. Forward about 8 years later and I continued doing those lifts: deadlifts, cleans, etc. I always focused strictly on my form, but I also challenged myself and kept adding weight as long as I could lift it properly. Well, about two years ago I was in the gym deadlifting a significant amount of weight. I was going for one rep. As I was slightly above my ankles, I felt my form slip very slightly and my lower back just collapsed. I spent the better part of the next year rehabbing and doing physical therapy to help repair a buldging disc. It still hurts me to this day and to counteract it I have to keep my core (abs) very strong. That being said, I do cardio every day and am in the gym doing bodyweight/light HIIT six days per week.
My takeaway from all this is that certain exercises, even if you know what you're doing, may not be worth it. I was training simply to be fit - that was my goal. Deadlifts will absolutely make you stronger, but they are also incredibly dangerous if your form deviates even slightly from where it should be. Today I'm happy and seeing great results with bodyweight exercises, light weights, and a proper diet. Honestly, I feel better than I ever have besides aches in my lower back.