Both Stack Overflow and Wikipedia are Creative Commons licensed, so they can be reused and remixed freely. Contributing to them may not be optimal if your goal

Both Stack Overflow and Wikipedia are Creative Commons licensed, so they can be reused and remixed freely. Contributing to them may not be optimal if your goal is to maximize your personal brand exposure in search results, but it does serve a greater good, and it's very different from contributing to a locked-down, copyrighted repo like Facebook, Instagram, etc.