I'll give you that, since it's not meant to. But what it's meant to is to also get your proper footwork going, off both wings. If you do it properly, the feeling is you nearly wrap your racket over and around your ball, so you get extended contact. But this contact is not "hitting through 3-5 balls", it's hitting around the ball, putting topspin by running the strings fast along and around the surface of the ball. Now, the only way you can achieve this is by staying with the ball and actually gently extending along the forward path of the ball after contact. And because you're doing it in slow motion, it makes it easier to synchronise your pushing forward off your back foot (which starts putting your body mass into the shot), the uncoiling of hips and shoulders (back to square after the shoulder turn) and your racketarm coming through into contact as the next link of the kinetic chain.
I find that when I don't do mini-tennis in the warm-up I mishit a lot of early forehands, because I misjudge the contact point (it gets too close to my body), and in order to make room for the swing I fall away from the shot - whereas with mini-tennis, I lock onto a contact point in front of my body and then I have the space and time to get my weight forward and into the shot.