What git log shows is not "a lie", it is a part of its data model. Git is all of its commands, not just the low level details. Commits are both snapshots of the entire repo, and diffs, and delta compressions - none of these is "a lie".
> Commits are both snapshots of the entire repo, and diffs, and delta compressions - none of these is "a lie".
Commits are never diffs. Commits are snapshots, and sometimes git computes a diff between two commits. Commits are also never delta compressions, but can be stored within a delta-compressed packfile.
Whether you like it or not, git is primarily its low level details. The porcelain stacked on top changes, and differs depending on the user's client (e.g., a GUI using libgit2). However, that "git log -p" is "part of git" that git log -p is not trying to convince you that commits are diffs and show you a true chronicle. It instead assumes that you know what commits are, and that you are asking for an easy to read overview of what has been going on.
Accepting that commits are always solely snapshots will make the issues you run into when working with the porcelain easier to understand, especially when exposed to more than one client.
(Knowing about packfiles and delta compression can also be useful when looking into performance/resource utilization.)
