What does the length of the method chain have to with anything? Let's say I define an interface Foo.bar.xyz with method call, and I call the implementation foo.

What does the length of the method chain have to with anything? Let's say I define an interface Foo.bar.xyz with method call, and I call the implementation foo.bar.xyzimpl.method() Everything is just as testable and decoupled, it's just a different project structure. Method chains have nothing to do with the things you stated.