They are. It could be that this particular style doesn't do a good job at it differentiating it.
So the user doesn't know if its either a new article, comment, etc.
If you are referring to the Forums TAB itself, Core XenForo does not use the ['counter'] element for any of the core Navigation Tabs. The Forums navigation tab does NOT have an unread Threads indicator, nor is there any code that makes Forum Tab sub navigation elements BOLD.Kind of like the same behavior with unread forums?