Clearly there is an ordering between commits -- parents and children -- but I don't see commits as having much temporal value.

Branches and commits can be merged and rebased left and right, and it only seems to follow that commits have an intrinsic state that's (not to be cliché) timeless. Patches and commits, regardless of when they're written, provide changes and accomplish X Y and Z -- it's only when one runs the code that time comes into play.

Semantics, I suppose, or I have had too much coffee this morning.