The long running CISSPforum mailing list on Yahoo Groups is being closed by ISC2, effective June 15, 2018. An alternate mailing list, run by volunteer CISSPs, has been created on groups.io. But the reason the CISSPforum is being closed is kind of interesting.
ISC2 itself isn't saying much about why. But most people discussing it seem to think it has to do with GDPR. Yahoo has not had the greatest success with security, so ISC2 may wish to limit it's exposure.
Yes, you are correct. That Web page is one of the postings on the new, supposedly private, "community" that ISC2 has created to replace the CISSPforum mailing list as a communications venue for the membership. OK, as a member, you are reading this posting on the "community." But you don't have to be a member of the "community." Anyone can read this posting. All you have to do is give them the URL: https://community.isc2.org/t5/GDPR/GDPR-and-killing-the-CISSPforum/m-p/11172
You will be able to see all kinds of discussion on the new forum. Do a Google search with any term you want, and include site:community.isc2.org as a term, and see what the amazing dancing CISSPs have said about it. (There is one area of the "community" that is not searchable, the "CISSP Group," but it's fairly small.)
Other posts: https://community.isc2.org/t5/forums/recentpostspage/user-id/1324864413
This message may or may not be governed by the terms of http://www.noticebored.com/html/cisspforumfaq.html#Friday or https://blogs.securiteam.com/index.php/archives/1468