The example shows three extra lines of code, two of which are `defer`s. I'm not an expert in Zig and can't tell you whether the example they give is contrived, but the claim they're making is way more than "a wrapper type".

> And that is considering humans write the code manually. Why does it matter if agents write the code? This makes no sense.

Because the particular form of non-ergonomic code that is demonstrated here amounts to a quadrupling of tokens. That's a substantial hit to the context window for safety that isn't even statically enforced.