I've always found this weird. I think to be a good software developer it helps to know what's happening under the hood when you take an action. It certainly helps when you want to optimize memory access for speed etc.
I genuinely do know both sides of the coin. But I do know that the majority of my fellow developers at work most certainly have no clue about how computers work under the hood, or networking for example.
I find it weird because, to be good at software development (and I don't mean, following what the computer science methodology tells you, I mean having an idea of the best way to translate an idea into a logical solution that can be applied in any programming language, and most importantly how to optimize your solution, for example in terms of memory access etc) requires an understanding of the underlying systems. That if you write software that is sending or receiving network packets it certainly helps to understand how that works, at least to consider the best protocols to use.
But, it is definitely true.