@JakBB: I do not let in fake accounts, disposable accounts (active but with a fake handle as a name), business accounts (accounts used for marketing and other specific uses), and empty accounts (I ask for some info personally before I let them in). Right now, 99 % of people in there are using their personal IDs, and all are verified wm users. There is absolutely no spam and unrelated content in there because of these policies.
@sfriedberg: If you don't like facebook platform, you will probably gain nothing from it either. This forum is the only official communication platform for world machine, so you are not missing a lot.
The main reason slack group failed was because not one of it's members was comfortable with the platform. It's uninspiring to communicate using tools of that kind, unless it's directed towards a specific purpose (like beta testing group, bug reporting system etc). The purpose of the facebook group is to provide a platform for facebook addicts like myself, to communicate about world machine using familiar systems. If you're not interested in joining facebook, or joining the group itself, you don't fit that bill. It's not a gallery, or a content stealing platform, there are just too many of those. You want to see content, you commit to the group spirit. At least give up your valid identity. That's the point of a closed group.