Much of the problem, I think, is that:
1) an idealized PDP-11 (I absolutely take Warner's point that that idealization never really existed) is a sufficiently simple model that a Bear Of Little Brain, such as myself, can reason about what's going to happen in response to a particular sequence of instructions, and get fairly proficient in instructing the machine to do so in a non-geological timeframe.
2) a modern CPU? Let alone SoC? Fuggedaboutit unless you're way, way smarter than I am. (I mean, I do realize that this particular venue has a lot of those people in it...but, really, those are people with extraordinary minds.)
There are enough people in the world capable of doing 1 and not 2 that we can write software that usually mostly kinda works and often gets stuff done before collapsing in a puddle of nasty-smelling goo. There aren't many people at all capable of 2, and as the complexity of systems increases, that number shrinks.
In short, this ends up being the same argument that comes around every so often, "why are you people still pretending that the computer is a PDP-11 when it clearly isn't?" Because, as with the keys and the streetlight, that's what we have available to us. Only a grossly oversimplified model fits into our heads.
Adam