[dearrifling]

You can have unrelated commits and roots in a single git repo. No need for empty root commit.

[yebyen]

I think the payoff is for merging unrelated histories, that you can then rebase one history on the other, and present a new unified history.

Is the really only reason why people do this, so that you can rewrite your initial working commit in a rebase? I think that might be it. (You can't easily rewrite the initial commit with a rebase.)