It is not about Alonso, it's the car and changes Ferrari did few years ago to their clutch etc...also Massa takes equally good and even better starts. Also during Renault years Fisischella took great starts and it was thought Renault has launchcontrol system...Kovalainen was even better starter of the Renault tests
It is about both Alonso and the car.
I think everybody have acknowledged that Ferrari car provides its drivers with great launch and therefore a great opportunity and momentum going into first corners. But it is Alonso that, so far, have put his car in all right places to capitalise on what the car allows him to do.