> This doesn't seem specifically a linear vs distributed VCS thing, as much as it is a unique property of git. I previously used Mercurial, and at no point did I feel I had to understand how the VCS stores its commit graph in order to know what running some set of commands will do.

Ditto. I've used Darcs, Mercurial and Bazaar, all are distributed, all have various levels of issues, but none of them required that I understand everything from the storage model up in order to actually get a grasp on them. I still have better intuition for Mercurial than Git (and long for a number of its features like GIVE ME FUCKING REVSETS ALREADY) despite not having seriously used Mercurial in years and having no idea whatsoever what goes under the CLI (and not caring a whit).