Oh, believe me. I've had TONS of repetitive strain injury. More than most people, but I always recovered and my joints were just as good as before. I stand by what I said. Most injuries are preventable, and they are almost always reparable. Many people get tricked into having surgery when they don't need it because they don't know how to properly take care of themselves. The problem is that much of this stuff isn't mainstream. A tendon injury can seem irreparable if all you do is rest, but believe me there are certain methods, which I have used successfuly, to treat any time of repetitive strain injury. I've had tendon strains, muscle strains, stress fractures, and various other knots and strains, but I always recovered. Heavy weight usually isn't a problem unless you are a body builder lifting massive weights, in which case you can actually TEAR a muscle. Now THAT is a serious injury. It will recover, but it will take a long ass time.
No employer I know of ever checked people's lifestyles before hiring. That's because almost everyone lives and eats poorly. Screening workers for good health habits would take way too much effort for way too little gains.
Out of curiosity, have you ever run 90 miles per week, twice a day? I didn't think so. I had teammates who ran 120 miles per week. I couldn't handle that load with out repeatedly breaking down, but some can. Either way, you can almost always recover given enough time. The company doesn't want to give you that time, though, so you have to get surgery so you can keep right on slavin'. Surgery is what makes your joints weak and does irreparable long-term harm. You think it's the work that's destroying your joints, but it's actually the process of working and opting for surgery instead of recovery that results in the long-term weakening of your cartilage. The problem is that nobody really knows how to recover. Recovery, when done right, actually promotes long-term strengthening.