This is not for setup, but for ongoing use. In order to see all the Rachio devices on my account and switch between them I have to have Location Services turned on for the application. When I turn off Location Services I can no longer see my other devices in the app or switch to a different device from the currently selected one.
Requiring unnecessary services is a classic way to create security holes in a product, and in this case it’s a privacy issue as well. Rachio does not need to know where my phone is in order for me to switch from programming my front yard zones to my back yard zones.
This is with Rachio app version 2.7.0 on IOS 9.3.5