You're really stretching the point here.

First, having vending machines for hardware doesn't mean that an IT department doesn't have any say on what gets ordered to go inside.

And really, is there any measurable amount of theft by employees who get a drop of coffee on their keyboard, and either just throw it away and get a new one, or go home and sell it? And would this in any way cost more than what the company saves by streamlining the basic IT hardware procurement that goes with any large company?

Quite far-fetched scenarios you're tossing out at this point.