Have you ever given gym advice on the spot?

I've been hitting the gym for quite some time now. I wouldn't call myself an expert, as I've still got much to learn. However, I do grasp the fundamentals fairly well, like how to create a basic workout plan and keep proper form. There's an older gentleman I often see at my gym, probably in his mid-70s. I admire his dedication to working out every time I'm there. I hope I can be as active as he is at that age. But I can't help but notice that he's performing every exercise in a way that's quite incorrect - too much weight, swinging it around, doing partial reps, and setting up machines that are clearly putting strain on his joints. It's so bad that it seems like he might be wasting his effort. I've never felt the urge to give advice to anyone at the gym before, mainly because 1) I don't know what their goals are, they might be recovering from an injury or something else I’m unaware of, and 2) everyone is learning, myself included. The only time I'd step in is if someone might injure another person. That said, when I first started, a guy approached me while I was doing rack pulls and offered some guidance. I still appreciate his advice to this day. But I genuinely feel sorry for this guy; he clearly needs some assistance. Do others help people out in the gym, or is it preferable to just let them be?