That line should ring true for technical writers who neither practice simplicity of instruction nor adapt their instructions to the skill level of the audience for whom they are writing.
Technical writers are very smart.
They want others to know just how smart they are. And they do. That is why most laypeople, who try to accomplish tasks described by technical writers, cannot do those tasks. I have run across some truly great online instructions for creating graphics. I have also run across some rather pitiful ones.