Reading this article and its sequel, I feel like the author is handwaving one key bit. I absolutely agree with his position on dependency elimination as a prima

Reading this article and its sequel, I feel like the author is handwaving one key bit. I absolutely agree with his position on dependency elimination as a primary goal, but by saying "Oh, a class that operates on a dependency is hard, so let's not write those", and "We're not going to deal with interfaces" he's punting on the entire problem -- handwaving the hard bits and then ignoring the fact that they exist. At some point, your code does have dependencies. The entire purpose of an interface is to be able to specify what your dependencies are -- to be able to say "This is the smallest thing I need in order to be able to work". When untangling dependencies, adding that bit in there makes it very clear what the seams are -- where you can say "I depend on something that does Foo -- Feel free to replace it", rather than "I depend on this thing that comes entangled in its own network of dependencies".