Hello.
I haven't gone through the links provided in the opening post. However, it appears that Darren's recommendations pertain to the concept of (class or object) immutability - the general idea being that, once an object is created, its identity must be unique in your application domain. Note, however, this does not mean all class data members are constant - just the crucial attributes that 'define' the object. For example, a human being continuously evolves since inception. However, certain traits remain immutable, depending on the domain of reference: Biologically - DNA; Government -