This title is a bit clickbaity. To save you a click: the author's mistake was, as a designer, to stop writing interactive prototypes and to go back to making static screenshots instead.
I would take that a step higher in abstraction and say
"His mistake was to stop going above and beyond because someone told him it wasn't required"
The lesson we can all take from this is to give you absolute best - if your immediate manager(s) are not ready for it, don't stop just because they can't handle it.
"His mistake was to fail to defend a better, interactive workflow enabled by new technology that could have helped the company tremendously, and instead fell in line."
The lesson for me is, we have to think critically, recognize real opportunities for the company, and argue for them. To fail to do so is not doing your job.
