The "first in gets the pin" rule is another I've never heard of. I always try to get the pin, and if someone else beats me to it, then so be it.
When there is an elderly player, I not only try to get the pin for him, but I also try to get the ball out of the cup for him. God forbid he use the head of his putter to fish that puppy out.
I played with an extremely overweight fellow once who always used the head of his putter to fish the ball out of the hole. He was a client of my playing partner, so I didn't dare say anything to him about it. We just raced to get to the hole before him so he wouldn't destroy the cup. Personally, I don't think he was capable of bending down to get the ball. And if he was, he probably wouldn't have been capable of getting back up.