The point is, low-level, as the name implies, is at a lower level than high-level. So every once in a while, you'll run into problems at the higher levels, and you have to dig into lower level stuff to solve a problem.

So what do you do if you cannot because you have no conception about the lower-levels / overall architecture? I've seen PHP programmers run into bugs and throw up their hands and yell "It just doesn't work! But the bug cannot be in my code!". Of course the bug was in their code, they just have no deep understanding of even their own environment.