Yes, this plug-in requires a working XMLRPC.php and a WordPress.com account. These are both required in order to securely connect to our cloud services (eg our benchmarking API) which help power the plugin.
By using the same account and communications layer as jetpack we benefit from the incredible maturity and performance of that system, and we also help our users by not requiring them to sign up for a whole new service if they already have a WordPress.com account.
If you already have jetpack installed we allow you to automatically reuse that connection without needing to sign in again. Other plugins that do this include WooCommerce and WCPay.