I think we're on the same wavelength here but coming from two slightly different angles so I'll try and be more precise about what I meant.
My intention was to warn people that:
(a) some printers can't print on the whole physical page (as already mentioned by utnik), and also,
(b) any use of a "shrink/fit" option could ruin the original intent regarding the aesthetic positioning of something on the page in respect to the physical medium (tmt53 didn't want a gap at the bottom of the page).
Specific positioning of something on a PDF page doesn't mean that it will, or can, be actually physically printed in that specific position on the paper (or whatever you're printing onto).
In other words, as you can't know for sure how people will print something, you shouldn't make assumptions about their hardware/software limitations or configurations. If you can't control the printing mechanism you shouldn't expect to know what the result will be in all cases.
Anyway, I hope I've made myself clearer for people reading this and apologise for any confusion caused.