I have read the docs page. Seems to me that blogs are either on for everybody, or off for everybody.
Is there any way to create a sort of site news blog for just the admin, while blogs are off for everybody else?
What would be the purpose of the admin blog?
Would Announcements forum on front page provide what you seek? (Just don't force subscribe all users on the system to it or they would all be getting email per posting).
A true WP blog could be installed and used on a moodle site.
Since WP has built in updates, might be easier to maintain/update as well as upgrade than the Moodle itself.
'SoS', Ken
You could change all other roles to not allow blog posting, editing, etc and only allow viewing and searching.