Printers are full of liquid ink, loose toner, and delicate moving parts that all cause problems if you skip prep. Ink cartridges leak, toner spills into a fine mess, and an unsecured printhead can rattle out of alignment. A few minutes removing consumables and locking down moving parts saves a big cleanup and a broken machine.
Pro tip: Bag toner cartridges carefully. Toner is a fine powder that is hard to clean if it escapes.
Watch out: Always remove ink and toner before moving. Cartridges leak and loose toner powder makes a stubborn mess.