The idea was you have all the methods on the object available in a small list, and (originally at least) it aided one pass compiling. Delphi continues this and in the IDE you can just go Ctrl-Shift-C in the definition and it will fill out all the method implementation boilerplate automatically, you can then ctrl-click between the implementation and definition. It is useful, say you're in a method body, you ctrl-click to get to the definition, then ctrl-click to the next implementation body you want to code. It means the code is easier to find than in say something like C# or even swift where you can have methods all over the place.