When designing for universality we design for a common dominator. Something we all do the same, a feature we all share (sit when we drive, walk on 2 legs). Reality then reminds us that universality is futile, we’re not all the same, and that if you look close enough the entire world is made of edge cases.
Once we get more personal with our constitutes (users, friends) it is easy to see that we’re all unique. In some way designing for a common dominator is like writing a script for a date beforehand, with a bunch of a if-then forks in your text.
Design for agency is like going to therapy. It is much more meta, and speaks to the forces of decision making and self fulfillment we all share.