Instead, Cagan slotted UX design (the function best suited to catch that risk) into the “usability” bucket, and many PMs followed.

As a result, the majority of time designers spend on product teams is dedicated to solving tool problems rather than goal problems — how to make a feature more usable, or how to add more options and settings. And given that every tool problem is by definition a problem created by the team, the overall impact of solving those problems is extremely low.