It's more nuanced, but it's also really simple: designers should understand their materials.
Say you're a carpenter. A true craftsman. You know all about the potential and the constraints of wood. You know how to design and make a great chair.
But now you want to make a thousand great chairs. You'll need to teach others your mastery. You better write some really good instructions. Keep a close eye on those chairs, from start to varnish.
And so you do. And because you know what you're talking about, your new crew trusts you. Some actually follow your instructions. Others surprise you with their creativity. But you're all building great chairs.
♦ ♦ ♦
Snap. You're a designer. You don't know any code. Code? A picture says more than a thousand lines.
You're the king of mocks. But your pixels fall flat when the engineers try to bring them to life. They're unable to grasp your vision and make everything work perfectly.
They have questions. A lot of questions.