Allowing advanced users to discuss topics above the basics of using the tool. Topics like: AI, API Calls, Custom Objects, etc.
Allowing us to do #1 outside of the structure of Facebook which lacks the ability to organize discussions into topics and find older content. (Remember the good old days of forums?)
Allow advanced users to use the Communities feature on a regular basis to learn it so we can decide the best way to use it in our business and in our clients' businesses.