Sure, I know now exactly what happened, and what I should have done in order to avoid it. My point here is that "Git repo is immutable and cannot lose data" is

Sure, I know now exactly what happened, and what I should have done in order to avoid it. My point here is that "Git repo is immutable and cannot lose data" is a lie, and people who believe it (like I did at the time -- hey, if anything breaks on rebase, I can always git reflog and reset to good state, right?) will have a bad time at some point down the line, so it's better to stop this lie from spreading.