Do you mean why the topics in the forums New and Announcements are read only? That is because it is only drawing attention of our forum members to the news or announcements made elsewhere in the openSUSE community. When that “elsewhere” is a discussion, you can go there and discuss.
When the “elsewhere” says it is a discussion, but you in fact can not discuss there, that is beyond the power of the forums. The News and Announcements are only automatic copies of what is posted “elsewhere”. And adding posts here would be useless for those who are watching/discussing “elsewhere” where the party is. Enjoy it or not.
Looking more closely - the original article does have “Start discussion” link which points to the locked topic on this forum.
I do not know whether it worked in the past with old forum software, but I personally do not see any harm in allowing discussion. And if you (forum administrators) decided that discussion is harmful, maybe you should communicate it to news.opensuse.org administrators so that they no more add discussion links.