Because it’s on WordPress, you have control over the look and feel of the site.
Plus all the conversations are stored on your server, and you’re not competing with ads on a social network like Facebook.
You can also give people the option of using an anonymous nickname if they would rather not share their real names.
Plus you can have better organization, with groups and discussions associated with each course or offering.
You can change the group settings at any time. Upload a new group header, or move the group to another area of the site. It’s up to you!