I don't know how old you are but joints wear out with most people. Exercises that hurt isn't always the result of a lack of mobility work. Guys that have been to war with weights from their teens to their sixties have damage in general. Ruined shoulders, knees, elbows and hips are common. I know there are exceptions like the big fat 65 year old guy that does three lifts and still puts up good power lifting numbers.
Strength is important but it's pursuit often leads to damage to your body. That damage can include joint, tendons, torn muscles and ligaments. Many guys in their 60 have said a variation of if I known I would still be training hard at this age I wouldn't have.... fill in the blank in my younger years.
As you age good health and fitness is becomes increasingly important. That's why I mentioned the various components in my prior post of strength, explosive power, endurance, VO2, mobility and balance.
54.
I do get the joint pain part totally, and I have a slap labrum tear in my right shouler.
What I have found is I can still lift what I consider heavy for my age/weight, but it just takes longer to recover - like I can make strength gains with 8 days between major lifts.
I just think it would be even better with a mobility focus.
Yesterday's workout:
15 min warm up - airdyne, sleds, plyo, bands, warmup sets on squat/bench
30 min e2mom: Squat x 5 / DB bench x 5
10 min: Airdyne - cycle 50 sec / sprint 10
5 min: hold bottom of squat and stretch.
I think that combo covers a lot of what you're saying, but maybe I'm wrong.