I don't know where this "invite only" stuff is coming from. I was not invited, and had no relationship with anyone on the site, and no public profile of note. I

I don't know where this "invite only" stuff is coming from. I was not invited, and had no relationship with anyone on the site, and no public profile of note. I signed up because I was curious what they were doing, and was added in a few weeks. That's not to say they don't have some system of prioritizing sign-ups. Perhaps they do, but regardless there doesn't seem to be any method in place to prevent people joining.