But destructors also don't conditionally interrupt the flow of execution, and always run at the end of a block.

> If I see a defer

The point is that you're not seeing it. In order to know if there's a defer happening at the end of a function you can't just read the end of the function, you need to read the entire function. That's non-local reasoning, which is what Zig professes to abhor.

And in fact defer is worse than destructors here, because a destructor runs the exact same code every time, whereas defer allows arbitrary code, so you need to review every single usage. And you also need to remember not to forget to use it in the first place (which is the classic footgun with defer), so in addition to vetting everywhere you use it, you also need to vet everywhere you might have forgotten to use it.