My cat door is badly designed for humans: I can't even figure out how to get my head through it. My cat can figure it out just fine.
My day job collects data from some sensors and uploads it to another computer. This computer-computer interface is not for humans, even engineers have trouble understanding it, but the computer does fine.
Both of the above cases are a design that is not for humans, and the engineers behind either have no need to consider design for humans.
Is it a backhanded insult? Ie is the tacit point that design which doesn't follow whatever guidelines is therefore not built 'for humans'?'