If you're used to working with a monolithic kernel like Linux or Windows, you might be inclined to start all your drivers before you start any applications. But with a microkernel OS, you have more flexibility and can reorder some of your startup program to take advantage of any idle time. That includes starting applications before starting drivers, wherever it makes sense.
A good example of this is the network driver. While some applications require the network stack (io-pkt) to be up, camera applications typically don't need the network device driver to be loaded or network connectivity to be established to show a graphic on the display. In this scenario, it's a good idea to launch your application before you start the network driver. Although other applications may require io-pkt, only those applications, and not your camera application, should have to wait.