At Google, people have built both, and we use a version control system on top of a snapshoting filesytem. The snapshotting is for never losing code/state on you

At Google, people have built both, and we use a version control system on top of a snapshoting filesytem. The snapshotting is for never losing code/state on your machines, and the version control system is for interfacing with others (code review, merging, etc). While you could use one system for both, having both layered on top makes it easier to change them to each specific workflow.