I really like her point about "learning disabilities." It is a really interesting way to look at it and a way I had never thought of before.
I think my favorite part is:
You stop thinking of people as "stupid."
Tags like "stupid," "bad at ____", "sloppy," and so on, are ways of saying "You're performing badly and I don't know why." Once you move it to "you're performing badly because you have the wrong fingerings," or "you're performing badly because you don't understand what a limit is," it's no longer a vague personal failing but a causal necessity. Anyone who never understood limits will flunk calculus. It's not you, it's the bug.