Git log (and many other tools as well) pretend that merge commits do not introduce changes. I learned about it in the hard way when someone managed to implement

Git log (and many other tools as well) pretend that merge commits do not introduce changes. I learned about it in the hard way when someone managed to implement an entirely new feature, contained within a hidden merge commit. It's only partially the fault of Git - the entire idea of a merge requires new concepts like 3-way diff, which are not needed for rebased commits. I'm not even sure that most software like GitHub can display such a diff.