It's about more than function.  Question and Article are pretty specific and I feel like many things won't fall into those categories.  Here are a couple examples:

What is your favorite public cloud provider and why? (Discussion)

Development teams and namespaces (Discussion)

Getting my head around a class model (Discussion)

2015.1.4 maintenance release now available (Announcement)

Alert: Incorrect SQL Results (Announcement)

And honestly I'm generally not interested in articles, nor do I have time to read them.  It would be cool to just view all questions or all discussions.  So that's one functional reason.

Can you add the weird issue of CKEdit not wrapping words properly to the bug list? It seems to just wrap lines right in the middle of words now.  I had never noticed this until today, but it's possible it was happening before or maybe it was just something wrong with the two posts I looked at before this one.  I guess we'll find out with this post because it is way longer than necessary just so I could test the issue myself.

:)

p.s. "Join the Conversation" is back? Aggghhhhh! :)