Weights, especially if done in the extreme and with bad form can cause deterioration on the joints. Take an extreme example: Ronnie Coleman, 7-times Mr. Olympia

Weights, especially if done in the extreme and with bad form can cause deterioration on the joints. Take an extreme example: Ronnie Coleman, 7-times Mr. Olympia winner( bodybuilding). Apart from the insane amounts of drugs these people inject themselves( bodybuilding competitions are the only "sport" that doesn't test the athletes for steroids), this guy was training with free weights at the extreme. We are talking about 800 lbs squats etc. He has had 8 spinal disk surguries and both his knees replaced. Compare that to Phil Heath, the current mr Olympia winner for 8 times in row( I think, could be 7). He is using mostly machines and so far( he is pretty old at this point) hasn't had any major injuries. So my point is that although machines are proven to not increase functional strength( due to the isolation of the joints), at some point weightlifting can be detrimental. I don't know if the person you are talking about took it very far or not but it certainly sounds like the type of person that would.