This explanation always messes with me... Why are you trying to build up objects and pass them into places? (er, sorry, I don't mean you of course, I just mean in general) When / why is that ever a thing that someone needs to do so often that it becomes a concern? How come I rarely if ever see this in the e.g. python or C++ world? I get the idea of decoupling component implementations from their host objects but I just can't see most use cases needing that level of generality. Especially when it comes at the price of smearing a big and complicated IoC framework all over your code.

Past a threshold of codebase size and complexity, I see the value of course, but IoC frameworks get pitched too often as a thing that everyone should be using IMHO. Even for testing we already have mocking tools that handle replacing component objects with mocked versions just fine, and we don't need IoC tools for that.