Doing push ups on a closed fist is easier for some people (me) because they have wrist issues. I'm not sure that I do them exactly the way I should, but when I do them that way I'm not putting weight on my closed fingers. I'm actually on the distal metacarpals making a straight line from where I'm contacting the floor up through my wrist and forearm. It took a while to get used to that. I also use the perfect push up system which is a lot harder, but still is easier on my wrist.
Gray