Why is there no generally accepted system of disease classification?

I am reading Burket’s Oral Medicine: Diagnosis and Treatment, Chapter 1 – Evaluation of the Dental Patient: Diagnosis and Medical Risk Assessment.

Under the section ‘Establishing The Diagnosis’, the author has to say this:

Unfortunately, there is no generally accepted system for identifying and classifying diseases, and diagnoses are often written with concerns related to third-party reimbursement and to medicolegal and local peer review as well as for the patient’s disease status*. Most practitioners probably follow the systems of disease classification and nomenclature that they were taught during their training since these usually serve as the framework for the mental models of disease syndromes on which they base their diagnoses.

*The author gives a reference to a study/report by Feinstein AR. ICD,POR, and DRG. Unsolved scientific problems in the nosology of clinical medicine. Arch Intern Med 1988;148:2269.

I couldn’t find the above-mentioned study/report on Google.

Along with the main question I would also like to know why are diagnoses written with concerns related to third-party reimbursement, what are these concerns and does it mean falsification of medical records?