Men.com has a whole sub-site devoted to it (“ Top To Bottom“). Boomer Banks recently did it for Raging Stallion. Being a “top only” gay porn star was a lot more popular in the 80’s and 90’s (e.g., Jeff Stryker, Mike Branson), but now, even the biggest tops end up bottoming on camera in an effort to expand their fan base, open new doors sexually, and create hype for a studio.