By default, not all categories on the left are enabled.
It took me quite some time to realize that there are more categories under “all categories”.
Then I was able to the pen to edit it to enable all categories.
Why are not all categories shown on the left enabled by default?
I don’t think this is user friendly and a little bit obscuring.
I believe it is because the volume may be too much for some new users?
Perhaps something more can be done to introduce new users to some of the configurable options such as category display list edit option. Although I think I would agree with a limited number of categories shown at the start, it should be pointed out how to change this.
I think new users might miss out because of it.
If it is too much, it would be still possible to edit them away.
Only thing that I think is too much are these Discourse badges. In every new Discourse forum you get bombarded by them in the beginning 
All categories should 100% show by default.
