Much like this forum, horse people generally enjoy the company of other horse people. I own a grade mare right now and I have to admit I kind of miss the feeling of being part of AQHA or the Jocky Club. Did I go to meetings? I didn't even show. It was just fun to belong. Microchipping may be fine, as is branding, but maybe those of us with "mutts" would like to have a that sense of belonging as well. Yes, sometimes joining a registry is that something that gives us the feeling we are looking for. The op said it was for identification, yes I saw that and don't need it pointed out, but I was just putting in my two cents about why someone with a grade would like to be registered.