It IS a piece of machinery. Apart from the screw, you have the nut (or half-nut), the release mechanism if it's a half-nut, the guide through which the moving jaw passes through the fixed one, and, very importantly, the jaws themselves.
For serious work a swivel-head vice is pretty naff. By all means have a separate vice for fancy work, but you can't beat a proper machine attached to your bench with three bolts (correctly, so that the fixed jaw is slighly proud of the front of the bench to enable you to hold a length of metal vertically to file or whatever the end of it).
I have a Record 4" bench vice (a number 2?) which I got as a birthday present about 48 years ago... and it's still going strong.
(I've developed other vices since then!)