I agree about age and injury but your post sounded like it was some sort of unique thing that the Lakers needed their two best guys on the court to win, obviously the Nuggets do to. Glad you clarified it.
Lebron is incredibly unique in his stamina. He's not the player he once was but he still really doesn't seem to get all that tired. Maybe he's tired when he reverts to his broken jumper instead of driving to the rim, I don't know. Davis is a different story, he totally dominates and then sort of floats around. Injury and minutes are always a concern with him.
Jokic and Murray while much younger are also in a bit of a unique position. Jokic is asked to do more than any player in basketball. He's their one big guy. He's supposed to do all the rebounding on both ends, lead the fastbreak. Bring the ball up often. Play out of the post, play out on the perimeter. Orchestrate their entire offense. It's a lot for a center carrying 285 lbs. Murray hasn't played in basically 2 years, it's a lot for a guy coming back.