Really, could anyone handle more than a few layers at the same time? It is sometimes useful to know how hardware (I'm looking at you, L2 cache!) works, but even then a bit simplified version can do the job.
And from time to time there comes another layer on top of everything else, and you wish you could forget the lowest layer you know, just to not start going insane. Or at least to slow it a bit :)
Unfortunately you can't forget about the L2 cache. I love Radix sorting it's just so fast and elegant except it's not vary cache friendly so it can be rather slow when you least expect it.
And from time to time there comes another layer on top of everything else, and you wish you could forget the lowest layer you know, just to not start going insane. Or at least to slow it a bit :)