It used to be more incognito than it is now. Back in the day it blocked all cookies and sessions like it does now, but that alone was reasonably sufficient. Now there is tracking built right into the browser by Google, cross site scripting is common despite it violating several security standards, browser fingerprinting can isolate and identify you, and a lot of other general fuckery. It wasn't always this way. They should update it to say "no browser history mode".