The author doesn't seem to understand where to use DI and where to use a Container. DI is used in the context of library code. E.g. the main business logic cod

The author doesn't seem to understand where to use DI and where to use a Container. DI is used in the context of library code. E.g. the main business logic code library. This allows you to Unit Test your business logic. A Container is used at an application level, i.e. the application that uses the business logic library. Maybe you're using a web framework. It's then the web framework that has ownership of the container. I.e. framework + business logic = application.