User blog comment:J.hustlah08/Some realizations/@comment-26058050-20170512144940

Dorry and Brogy's fight is a matter of who is more worthy to go back to their homeland as the victor. It's realistically a matter of pride, but giants take it very seriously.

Also it's the world of OP, what's wrong with having abnormal skin? Have you seen Kaido? He just simply cannot die. Teach is another example of having an abnormal body being able to use two devil fruits.

As for age, you know that Whitebeard was 72, and was still kicking ass right? Garp is older at 78 and is still a major threat to pirates across the world. Age is less relevant if you still can do major damage