What do y'all think about pinning/alpha roll

I have heard some people hate it and some people love it, or at least think it's a natural training method. I have never done this physically to my dogs but my pup Riley will submissivly roll on his back when I give him the "You're in trouble look." I used to get on the floor and play with him and that's when he started doing it. It would be when I would love on him and put my face around his neck. That's when he would automatically do it. Now he just does it if I give him a certain look, or when I give him a good ole belly rub! What is your opinion of people who purposfully incorporate "Pinning" or the "Alpha roll" for training?