The head dip is used by everyone. obviously not the same thing as a dive but its an attempt to get yourself across just a 100th quicker
Case in point. It's not like the dive. The head dips while running, while a dive is literally suspending yourself from the track, feet off the ground. The torso will hit the finish if it's in a horizontal position before a slanted vertical position. The difference is that a head dip is an orthodox way to cross the finish while a dive is not. I doubt any track and field athlete routinely dives into the finish line every race in order to inch along a win.
It's not like the dive was never done before. See the 2008 olympics where USA won bronze in 2008 doing the same thing.
Say this happened in the men's 100m though and there would be hell to pay if
theoretically someone had the speed to barely beat Usuain Bolt with a dive.
As i stated I'm not here to argue the rules. I think she won and should keep her medal, end of stoy, but it's not like everyone was gonna sit there and clap for her for winning like that and their feelings aren't unjustified.