Purpose of Medical Evaluation?

My assumption is that the purpose of the medical evaluation is (i) to confirm that the prospective employee is free from infectious diseases and would not pose a public health risk to the Kingdom's residents; (ii) to confirm that the prospective employee is drug fee; and (iii) for prospective employees whose job function would require physical activity, to confirm that the candidate is physically capable of performing the job function. Are these assumptions accurate? Should a prospective employee seeking a sedentary, office position (e.g., accountant) need to be concerned about failing the medical evaluation because of ailments such as hypertension, elevated cholesterol levels and the like? Thank you in advance for your feedback.