From any machine who has checked out the code? That's sort of the point of git. Any cloned version of a repository is a "git server" in itself.
DVCS is designed to propagate code to many people and allow them to easily modify and share with others who also have a copy. If people don't have a copy they can get a copy of a copy (which at some point may have been modified). In a large company you need a Single source of centralized truth. You cannot build a company on the concept of "it works on my dev workstation" or the worse suggestion here "all the company's IP source code is on only on my dev workstation".