I would guess the canonical example of this is goto. By the definition the author uses, goto is extremely powerful. At the same time code written with goto is g

I would guess the canonical example of this is goto. By the definition the author uses, goto is extremely powerful. At the same time code written with goto is generally a complete mess. Instead languages provide for loops and while loops which are more restrictive than goto, but much easier to reason about. (I'm working on a blog post about this.)