This labeler is a far cry from the modern tape dispencers we use to close boxes with, and it seems over-engineered. But in fact it isn't: back then self-adhesive tape was not a thing, so labelers were simply fed gummed paper that needed to be made wet and needed to be cut properly rather than ripping apart once the integrity of the label had been breached at the proper length.
In this video it is clearly shown that the labeler featured here has all those functions, which in modern designs have been migrated to the tape itself. Hence our tape dispensers can be simpler, with no water, a simple fixed cerated edge to cut the tape, and a plastic flap to help wipe the tape onto the box. As for the printing on the label tape, companies just order their rolls pre-printed, which is more cost-effective. Or they can just use standard blank or transparent tape.