500px is now strictly a service for sharing and selling “photography,” and it has been banning accounts that post images that aren’t “photographic” enough. The change in policy is so sharp that 500px is now driving away a user that it once featured as a “Photoshop master.” Polish photo artist Michal Karcz says he’s being kicked out of the 500px community despite the fact that 500px once celebrated his popular work. In his 5+ years on 500px, Karcz uploaded 173…