The commit graph should at lest have a disclaimer of some kind. Plus I think the lines of code added/removed are a better indicator than number of commits. Perhaps with some heuristic to detect whether a lot of lines were being changed similarly, such as if code was changed by a wizard or from a find and replace.

A colleague once showed me a tool to produce back dated commits in bogus git repos so you can draw pictures on your commit graph. You should know that people are gaming the gamification.