[mcnichol]

I think this has more to do with testing, maintenance, and how it simplifies portability/flexibility.

There is a point where software diving down meets the hardware coming up. When you import a library you start creating harder to separate internals and testing becomes more of a blackbox approach (I don't care what happens inside as long as my results are consistent) as opposed to unit and function. It eventually does reach a point where dependencies are harder wired but the deeper you can create this DI, the more dynamic things become (function arguments, library injection, os virtualization, even hardware at points [PCI-E, serial]).

I think you are right about DI being less common but that is because it's not a natural reaction until you reach the maintenance side of software. It's much easier (and more performant) to just load it up on startup and call it directly. When you get into the way languages work you will see DI is integral to their accessibility and maintenance.