Why does ABAP divide classes into implementation and definition?

Question

I know that ABAP objects are of some old nature, but as far as I know, you still have to use at least two "sections" to create a complete class.

ABAP:

CLASS CL_MYCLASS DEFINITION.
    PUBLIC SECTION.
        ...
    PROTECTED SECTION.
        ...
    PRIVATE SECTION.
        ...
ENDCLASS.

CLASS CL_MYCLASS IMPLEMENTATION.
    ...
ENDCLASS.

Java:

public class MyClass {

    <visibility> <definition> {
        <implementation>
    }

}

Wouldn't it simplify / speed up development if it were combined like most modern languages?

What are the reasons for this separation?

Answer 1

/ (), : , , , . ABAP - , : Pascal , Object Pascal . , ++ ​​ , -.

Answer 2

, :

(?) , SE24. dynpro .

, . .