I don't think that's strictly true, as I can give it a new gui or tui program it wasn't trained on and it will learn it. Unless you're talking about general abilities like sight, but the same is somewhat true of humans.
The claim is furthermore that truly original thinking, the infamous leaps in understanding and creativity, happen by attaining points outside such a convex hull.
It's hard to rigorously verify or disprove this claim. Hopefully this helps build an intuition of why the claim is not as shallow and obviously wrong as it may seem initially.
But yes, metaphorically I think that's right.