Simplicity is relative to who you are designing for. Not all tasks are going to be incredibly simple but they may be exponentially simple compared to the alternative. For example: our software we have incredibly complex processes for Quantity Takeoffs which to someone unfamiliar to the process in general can seem daunting but compared to the manual process cuts down on potentially hundreds of hours of manual calculations.
Sometimes there is a certain level of complexity that is necessary to give the user enough control to do their jobs. Not every task can be accomplished "in seconds" or in "just a few clicks". As designers we should be very aware of where in the spectrum users fall and be able to make their tasks much easier to accomplish in relation to what they would have done otherwise.
I find shitty the argumentation of the article. You can't compare a shovel with a digger machine. It's simply stupid. You can compare an steering wheel with touch controls, UI and OSs agaisnt F1 one, but hell, this is by no means, something comparable.
Same things I see when people brings Dieter Rams to the table. I've tested many apps that emulate DR designs guidelines and, while the apps look perfect, they were pretty much harder to understand. The more simple, generic looked the app, the more usable, according to our lab experiences.
"Simple" isn't even the goal of simplicity. Clarity (usability) and aesthetic freedom (visual design) are.