PayPal Payments for WooCommerce

Is there a way to have fastlane enabled as well as the setting “Force shipping to the customer billing address”.
If you have fastlane and this setting enabled you get the following warning:

Warning: The Shipping destination of your store is currently configured to Force shipping to the customer billing address. To enable Fastlane and accelerate payments, the shipping destination must be configured either to Default to customer shipping address or Default to customer billing address so buyers can set separate billing and shipping details.

I was curious if there was a specific reason to this?