Wait, I've been using Connect and I had no idea! Where do you find this feature?
EDIT: Found it! In the top-right ellipsis menu there is "View Instance", which has a button to show all communities there. That's a very neat feature that I wish was much more visible, to be honest.
Yes, this is required. This aids in the discovery of communities that the user may not have considered joining. Or they were aware of the idea but lacked a keyword to locate the community.