The chapter 'GA only with Genotype' (cf. 5.1) was a bit more general than the introductory example given by Goldberg in his book , but it accepted the general framework implied by this example. Specific for the general GA paradigm is the abstraction from the biological reality which differentiates between the genotype and the phenotype. As often allow generalizations the investigation of very powerful structures which otherwise would be 'obscured' for the 'theoretical eye', our mind. But abstractions do also loose some details which can be important.
For the reconstruction of biological mechanisms which enable 'intelligent systems' to appear on earth it seems important to provide one variant of a genetic algorithm (GA) which includes the differentiation between genotype and phenotype.