> It sounds obvious when spelled out but it blew my mind.

I think there's a weird thing that happens with stuff like this. Cliches are a good example, and I'll propose an alternative definition to them.

  A cliche is a phrase that's so obvious everyone innately knows or understands it; yet, it is so obvious no one internalizes it, forcing the phrase to be used ad nauseam

At least, it works for a subset of cliches. Like "road to hell," "read between the lines," Goodheart's Law, and I think even Amdahl's Law fits (though certainly not others. e.g. some are bastardized, like Premature Optimization or "blood is thicker than water"). Essentially they are "easier said than done," so require system 2 thinking to resolve but we act like system 1 will catch them.

Like Amdahl's Law, I think many of these take a surprising amount of work to prove despite the result sounding so obvious. The big question is if it was obvious a priori or only post hoc. We often confuse the two, getting us into trouble. I don't think the genius of the statement hits unless you really dig down into proving it and trying to make your measurements in a nontrivially complex parallel program. I think that's true about a lot of things we take for granted