Your heart is still moving the same weight, fat or muscle. It's the same from system stress. Experiencing more health issues from bulking even at >20 bodyfat is pretty common... blood pressure etc. At some point just being a bigger person who has to eat more takes a toll.
An example is sleep apnea, which is highly correlated with neck circumference and being “jacked” can often mean your neck grows as well. There are many “jacked” amateur and professional athletes who suffer from sleep apnea. (Something like 30% of American football and rugby players have sleep apnea.) There are a myriad of negative risks associated with it, from cardiovascular risks to dementia.
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.
Do you have evidence for this? (Assuming getting jacked without the use of steroids)