I'm not sure why you are providing that second link as proof that they don't log. That is just a link to the same story being discussed here and the same one I am quoting in my comment.

Also the first link continues its insistence on using the phrase "user activity" logging. That's a rather nebulous term. Nowhere is "user activity" defined and it's certainly not a term that meaning in the context of syslog/journald. Does "user activity" logging preclude RADIUS authentication?