When you start a Kobo e-reader for the first time, it blocks any interaction until you run the setup software (Win/Mac only) or connect the device to a WiFi point. This initial setup will do two things: it will force you to create a kobobooks.com account, and it will update your device's firmware.
Some users would rather not connect their devices to the internet or create online accounts because of privacy concerns, while others may not be interested in buying e-books on Kobo's online marketplace. Furthermore, there's no setup software for other OSes like Linux-based ones, so you're left alone with the WiFi option.