Body absorbs micronutrients and macronutrients in the quantity that body requires rest is removed out then how can we say that salt intake affects our blood pressure ?

Your underlying premise is incorrect. Overeating causes obesity. Excess intake of iron can result in damage to internal organs. Excess intake of salt raises blood pressure. Excessive intake of vitamin A and Vitamin D causes systemic disorders. Wish you good health!

Some do not regulate salt intake properly. For reasons that are not known if your BP is “salt sensitive” it will go up when you eat too much salt. Eat less BP goes down. Best diet to test in yourself is the DASH diet which lowers BP even in people with normal BP. Assuming you eat like most Americans. It lowers systolic in 1 week and diastolic in 2. If your BP is “salt sensitive”.