Bushing or not??

My new water pump came with a 3/4 x 1/2 HDPE bushing in the heater hose port. The old pump also had this bushing. The nozzle fitting has an adapter to go from 1/2" back up to 3/4" to accept the 3/4" hose nipple. Why bush it from 3/4 to 1/2, just to go back up to 3/4 nipple? Do I need to use the bushing?
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