Programmers.SE originally took "not constructive" questions, but that turned out to be a mess, so they had to refine their scope multiple times until a viable model appeared. Now their scope is more or less "whiteboard" questions, which can be partially opinion based (just like almost every question on SO), but that is not the focus. The FAQ says:

    > Specific issues with software development, for instance:  
      - algorithm and data structure concepts  
      - testing and quality assurance  
      - development methodologies  
    > freelancing and business concerns  
    > software architecture, engineering, or licensing