I felt that that the author was more concerned about ownership than short-term productivity or efficiency.

With ownership a different kind of productivity is evoked: knowing how (and why) every part goes together the way it does. This could lead to a flow state when managed effectively.

I do agree that these exercises could lead into the realm of yak shaving, but in this context we're talking about making personal tools vs tools for others to use. I think there's a big distinction between these two approaches.