That brings up a deeper issue with git's philosophy. Git's UI is largely geared to introspecting the repository history only insofar as it exists to the currently existing checkout--commands that interact with history without concerning themselves with the current checkout are far more inscrutable, confusing, and difficult to find.
By contrast, Mercurial's UI makes the repository history a more first-class citizen, and it is very easy to answer basic questions about the history of the repository itself. If you're doing any sort of source code archaeology, that functionality is far more valuable than comparing it to the current state: I don't want to know what changed since this 5-year-old patch, I want to know what this 5-year-old patch itself changed to fix an issue.
By contrast, Mercurial's UI makes the repository history a more first-class citizen, and it is very easy to answer basic questions about the history of the repository itself. If you're doing any sort of source code archaeology, that functionality is far more valuable than comparing it to the current state: I don't want to know what changed since this 5-year-old patch, I want to know what this 5-year-old patch itself changed to fix an issue.