Well yes and no. Strain on the skeleton from excess muscle isn't particularly a problem unless someone is really huge or does a lot of running. The skeleton adapts to handle the load. Having more strength in the muscles that stabilize joints actually reduces the risk of joint injuries — up to a point.
The medical problems with excess muscle mass tend to be more on the cardiovascular system than the skeleton. And the process of gaining a lot of muscle mass can increase the risk of musculoskeletal injuries (especially if using PEDS), which is a key confounding factor when looking at population health statistics.
The problem is not bone density. Your bones are never going to break under your own weight unless there's something seriously wrong with you. The problem is joint health.
Sure, guess I read your comment as bone-focused. That said, joints also do get more resilient when resistance training. Although, I'm aware not necessarily at the same rate as the muscles themselves, leading to issues where the muscles are capable of handling more weight than the joints can happily handle (if we are to personify joints). But, I think that issue is mostly obviated with good programming and load management.
