In my opinion the reason for this is that Discourse makes it easy to browse the latest topics from all categories mixed together. So rather than functioning as two fully separate sections, Help and support and General talk are just categories within the overall Discourse system. When viewing the top level topics page you see Help and support topics mixed together with topics from all other categories.
This reinforces the feeling that Help and support topics are just like any other Discourse topic and users communicate in the same way within them. To foster a different communication dynamic in Help and support, it would really need to be a completely separate section with a somewhat distinct design and where topics didn’t mix with those from other categories. I’m guessing this isn’t really possible within a single Discourse instance.