I have built many systems that were meant to be used seriously. Never once has my lack of understanding of graphics cards, for example, come back to bite me.

Every system is built on abstractions. You can argue about the value of understanding particular systems, but we are well past the point when any one person can or should understand them all. No one is arguing that it's acceptable to learn only the highest-level abstractions. But it is acceptable to let somebody else worry about some of the lower-level ones.

People who don't focus on understanding engineering systems often focus on understanding other systems––team dynamics, for example, or business needs. I've met a lot of developers who only cared about learning the technical side, and were happy to look down on developers who didn't feel the same. Is that wiser, somehow?