The standard git porcelain has it's problems, but they are largely irrelevant to the question of git's simplicity. Issues like --all/-A, or the -b flag of git-commit are unfortunate, but they do not affect the underlying simplicity that tytso is talking about. That underlying simplicity is what makes git a pleasure to work with despite weird porcelain because it allows you to reason about operations in git without reasoning about what different commands are for or can do.

If you want to know if some operation can be done, you don't reason about git-reset, git-checkout, git-branch, etc.. you reason about the DAG. After you have a solid mental image of what you are attempting to do to the DAG, it is a simple matter to decompose that action into a few weird but ultimately simple incantations with the porcelain. If you are interested in optimizing how many steps you decompose operations into, then you can learn the esoteria of a few git operations, but all of the hard thinking, the real problem-solving, was done in the context of a different abstraction.