Given that commits are immutable objects, the only sane interpretation of "rewriting history" is that it rewrites your view of the history rather than somehow rewriting immutable content-addressed objects.
Sure, but lots of people using git don't really understand that commits are immutable or that the commit tree is an append-only data structure. The pervasive use of the phrase 'rewrite history' hinders this understanding.
I disagree. I've used Git for a long time, and talked to a lot of Git users, and I've never seen anyone say something that implied they thought they were literally modifying the commit objects, as opposed to rewriting the history of a branch.