This technique definitely makes a difference. The bike gets a big push from the rider’s arms that causes it to get a good last minute acceleration. Meanwhile, the rider will be going backwards relative to the bike. This is why you see the sprinters get extended arms and sit at the very back of their seat when they do a good lunge.
The rider’s arms do work and that increases the total energy of the rider/bike system.
The same technique, although with less force, is used by good cyclists when they transition from pedaling standing up to pedaling sitting down. It is used to minimize the changes in speed as you change your position on the bike so the rider behind you doesn’t run into you.