It has the number of steps it does so that the pressure from the button holding your pants closed is evenly distributed over the fabric (and thread), so that nothing tears or rips. When sewing through cloth more points of attachment is generally better. You might be able to staple a button on without damaging the fabric over time, but it’s probably a lot less comfortable to wear than one sewn on.

Just attached a button to my pants yesterday, after the factory sewn button gave up.