Damyon,
In v 2.6 there was a feature called Submission comments (used to be labelled Notes) which allowed students to post comments to the Teacher about the assignment. This was configurable per assignment. The Feedback comments were for the Teacher to respond to the student. Now in 2.8 this feature has helpfully been removed. Could you point me to the thread where this was discussed ? I don't see how a site wide setting substitutes.
Now I'm confused about the point of Feedback comments. I've noticed that the Teachers often post their own feedback comments into the assignment submission comment area. Does this make a difference in terms of what the student can see ?