I get this question all the time..."why would I want to start a private online community instead of just having a Facebook page or group?"  The assumption behind this question, of course, is that a Facebook page is free (it is not, when you consider your time investment), and that the two are mutually exclusive (they're not).

But the question is backwards. You should first ask yourself what's your reason for wanting to start your own community.  

Is it increased revenue?

Is it better customer service?

Is it just for fun?  

Choose your technology to support your goals, not because "everyone else is doing it."  You aren't one of those people who would jump off a bridge, right?

Based on our experience, the ideal scenario is to be active in the social networks where your customers are most active, and then provide a deep-dive social hub on your own website.  

Build in "feeders" from your social outposts that bring members back to your site to continue the conversation and make purchases (if that's your goal).

A recent study stated the following regarding branded communities:

“We find that 19% of the post-launch revenue from community customers can be attributed to their joining the community. ...The analysis of community data reveals that social connections – the number and importance of friend ties – and interactions – personal page displays – are positively linked to social dollars.”  Social Dollars: The Economic Impact of Customer Participation

in a Firm-sponsored Online Community. Manchanda, et al., January 2012

Why would you want to build your own private online community?

• You get the SEO juice
• You build a database/resource you can use permanently
• You control the advertising
• No distractions of games, etc.
• You control the experience and change it to meet the needs of your audience
• You can contact your users when you want, on your own terms
• Your conversations can take place away from the watchful eyes of your competitors