The "Member Of" construct allows for bread crumb formation, and free association. It is very similar to Categories, but it is easier to spell, and provides a link to a page with content, rather than just a list. They work together!
If you create a wiki page, you shouldn't just leave it hanging! You should link to other related pages.
In this era of 30 inch hidef displays, that back button can be very far away!
Creation of superfluous Categories makes navigating the category page a pain! Humans work best with about 7 choices.