Why does decreased glycolytic activity impair oxygen transpo by hemoglobin?

2,3-Bisphosphoglycerate (2,3-BPG) is the most abundant organic phosphate in the erythrocytes. It is produced in the erythrocytes from an intermediate (1,3-biphosphoglycerate) of glycolysis. This sho pathway is called Rapapo-Leubering cycle. It normally binds to hemoglobin and decrease it's affinity to oxygen and thereby helps in oxygen delivery. When glycolytic activity is reduced, oxygen transpo by hemoglobin is impaired due to decreased production of 2,3 BPG. In hypoxia and anemia 2,3-BPG in the erythrocytes is elevated. Ref: Essentials of Biochemistry, Satyanarayanan, Page 108