Haha, it is quite a good analogy! The drives even contain schematics on how to build a really fancy computer, but they are very complex and if you try to change something it usually breaks down. So in the end you just write really simple instructions to each drive, throw them in a box, shake it, and discover that the drives themselves self-assembled into the computer you wanted.
Here's the summary for the wikipedia article you mentioned in your comment:
Gray goo (also spelled as grey goo) is a hypothetical global catastrophic scenario involving molecular nanotechnology in which out-of-control self-replicating machines consume all biomass (and perhaps also everything else) on Earth while building many more of themselves, a scenario that has been called ecophagy (the literal consumption of the ecosystem). The original idea assumed machines were designed to have this capability, while popularizations have assumed that machines might somehow gain this capability by accident.
Self-replicating machines of the macroscopic variety were originally described by mathematician John von Neumann, and are sometimes referred to as von Neumann machines or clanking replicators.
The term gray goo was coined by nanotechnology pioneer K. Eric Drexler in his 1986 book Engines of Creation.