And the PR author clearly doesn't even know why (he even begins the answer with "¯_(ツ)_/¯"). His only explanation is that it's there because it was in the code

And the PR author clearly doesn't even know why (he even begins the answer with "¯_(ツ)_/¯"). His only explanation is that it's there because it was in the code that he copied. So essentially he has submitted code that he doesn't understand and is angered when people ask him to explain it. It's their job to ensure that the code is there for a good reason. That is how the quality is upheld.