Some people apparently see two-shock rear suspension as old fashion and less effective. There was a time when the rear suspension of every motorcycle had a pair of shock absorbers attached to either side of the rear swingarm.
Yes, even those that were raced on tracks or those that jumped the humps during motocross. There still are quite a few motorcycles with just such a set-up but now they belong mainly to the eco-commuter or cruiser class. Nothing wrong with it as the twin-shock set-up is pretty effective considering the costs involved and the performance of the machine vis-a-vis the amount of desired suspension travel and control.
The whole idea behind a good suspension system is to ensure that it is soft enough to absorb the smaller undulations on the road and still enough not to bottom out on the bigger ones. This requires a progressive change in the leverage ratio as the shocks compress or expand.
The usual way of doing this was to incline the twin shocks a bit forward at an angle from the vertical. This would keep a more or less constant distance over the most used suspension travel range between the swingarm pivot and the shocker mount as the rear axle arced up and down in response to road undulations. This all helps the road handling of the motorcycle or scooter.