You've said it yourself: given a perfect recovery period, appropriate medical care, a healthy lifestyle (which also includes getting enough rest, proper diet, a good amount of motion besides the ones you repeat all day at work, and a means to resolve stress), you can recover from joint issues.
And injuries that go largely undiagnosed (my wrist hurts but I don't know why) tend to just get worse over time, especially if the action that contributed to the original injury is repeated over and over and over and over and over and over again.
So how many people do you think have access to appropriate medical care, are able to have a healthy lifestyle (if they are working as often as the examples in this thread suggest, plus a commute, for the amount of pay described), and despite being hourly are able to take off the days or weeks (or months depending on the joint) to heal properly, not to mention getting the physical therapy to assist with the healing process?