Well I wouldn't do it, but because it is a possibility, some people hope that it'll allow them to keep a rooster they've grown attached to, generally in areas where it's otherwise illegal.
"Neutering" (caponizing) is pretty tough to do, very few vets are willing or capable of doing it, so most people who know how to caponize do it at home. It's surgery, their testicles are inside the body up behind the ribs. So not really an option for most folks...