Palmer’s shoulder rotation as a young player was legendary… even as a Senior player he had a great turn. Nothing will rob an older player of distance and even accuracy more than the loss of shoulder rotational range of motion.
While it is inevitable some will be lost over time… still, much can be done to preserve this if you are aware if it’s vital importance and work on keeping both strength and flexibility there as one gets older.
We can learn a lot from looking at Palmer above. While I don’t know his workout regime over the last decade or so… he may very well have neglected to keep attention here.
We have some simple stretches and exercises in the student area that will do wonders to keep your golf swing functionally alive for a very long time.