Or used any vehicle with independent front/rear braking like a motorcycle or bike. The rear is for fine tuning while the front is for actually stopping.
Also anyone who has ridden a bicycle.
In that case, leaning back makes a surprising amount of difference.
They're both for stopping. It's why they're biased to have more power in the front than the rear. You can take advantage of this with the rear to "tune" in some situations, or to maintain stability at low speeds, but it should also be fully used when braking.
Also people who ride dirt bikes- the back will slide out fairly easily compared to the front (but using the front exclusively comes with some pretty big tradeoffs)
...or to anyone who ever rode a bicycle or motorbike with front and back brakes. Pull (bicycle) or press (motorbike) the back brake hard and the rear wheel tends to skid. Pull the front brake hard and the thing wants to somersault. The back brake is needed to stabilise the vehicle but the front brake does the real work.
Not on more modern cars. In an emergency stop situation the front brakes still do the work, but in normal more gradual stop situations traction control biases to the back wheels as much as possible so the front wheels can steer.