I don't think that's the issue, here: the person who opened the issue is complaining about legal mention not being there, not about the code being reused.
This is not a minor problem, because turn over is high in developers world. If you don't leave a comment mentioning the code came from somewhere else, it's easy a few years later for a new dev to think their predecessors wrote that code and to recommend their company to sue projects around where they see the same code (possibly without legal mention too).
Not to mention that when you give your code for free and make other people's job easier, the least you deserve is to be credited.
This is not a minor problem, because turn over is high in developers world. If you don't leave a comment mentioning the code came from somewhere else, it's easy a few years later for a new dev to think their predecessors wrote that code and to recommend their company to sue projects around where they see the same code (possibly without legal mention too).
Not to mention that when you give your code for free and make other people's job easier, the least you deserve is to be credited.