How many of these devices would you have to buy and throw away to match the environmental material footprint of even one 1U rack-mount server? They're tiny. Orders of magnitude matter.
(Similar effect: However "disposable" USB flash drives may superficially seem, compared to the floppies they replaced they are nothing. And I do not just mean that the USB sticks can hold lots of stuff... I mean that if you pile a normal computer user of the 2015 era's USB sticks in one pile, and a normal computer user of the 1990 era's floppy disks into another pile, the floppies would tower over the entire pile of USB drives and almost certainly have a much larger environmental footprint. I hedge only for the possibility that the nasty flash memory might dominate the floppies manufacturing, but the floppies do irreducibly have an awful lot more plastic in them, so I'm still guessing the floppy pile comfortably "wins".)