Critique doesn't always explain reproduction. That's more like a bug report I think. Actually saying what's wrong is describing that the UI has a clear problem with z-index. I would understand if someone was trolling the Apple bug submission process, but they aren't; they are pointing out flaws with clear visual examples.
I disagree that critique must inherently describe the problem. Sometimes, the problem is fairly self descriptive, especially with what this blog provides, which is obvious issues that most of the blog's audience will immediately understand as "sloppy" - that is, I shouldn't have to explain why the z-index issue is sloppy to justify my criticism, but if you want a bug report, I can explain how I got there.
I disagree that critique must inherently describe the problem. Sometimes, the problem is fairly self descriptive, especially with what this blog provides, which is obvious issues that most of the blog's audience will immediately understand as "sloppy" - that is, I shouldn't have to explain why the z-index issue is sloppy to justify my criticism, but if you want a bug report, I can explain how I got there.