Since you seem to be missing the point...
Here it is again.
Your attitude is that people should not use tools unless they know everything relevant to its proper usage. Your definition of what is relevant seems to be that if it might come up, then they need to know it. This is a circular definition of relevancy that justifies any particular dependency in hindsight as the user's fault for not knowing better.
Now I know that [link|http://www.joelonsoftware.com/articles/LeakyAbstractions.html|abstractions leak]. (That is one of the few articles by Joel that I agree with incidentally.) Furthermore I often find myself being in the position of being the person around who understands what abstractions leak, and why. There is no fundamental solution to that problem. Shit happens, and plumbers are needed for it.
However one mark of a programmer that you want to have around is the ability to see shit and recognize it for what it is. Leaking abstractions are signs of shit. While they may be inevitable, they are not something that you want to take lightly. Because a system built by people with too much tolerance for that inevitably degrades into a complete mess.
In this case the leaking abstraction is one of the worst kinds to have. Different filesystems use the same words for subtly different abstractions. This makes it hard for most people to even verbalize that there is a difference, let alone what it is. (When the same thing happens in speech you get classic threads where people talk past each other at length.) And when you try to combine them into one abstraction, the gaps keep on leaking past.
So yes, it happens for good reason. But it is a basic design flaw in the system. And it is not one to belittle people for getting tripped up by, nor is it one that has a simple right answer.
Cheers,
Ben
