Minimalism is one of those things where simplicity is the goal, but not the measure of success. It seems many people (I'm looking at you Windows 10) forget the design part of flat design. Making all the icons indistinguishable general forms is simpler, sure. This study makes the same mistake: it finds removing indictors of function make things harder to read. But they forgot to indicate function in other ways to compensate. It's as if you intended to prove goto isn't bad by removing it from a language without break, return, continue, or loops.