All the author is advocating is for software companies to be up front about what their software is doing.
(ii) Spotify has a right to allow the Spotify Software Application and the Spotify Service to utilize the processor, bandwidth and storage hardware on your computer or other relevant device for the limited purpose of facilitating the communication and transmission of content and other data or features to you and other users of the Spotify Software Application and the Spotify Service, and to facilitate the operation of the network on which the Spotify Software Application and the Spotify Service runs.
Granted, it's not listed as a "feature" but you agreed to the possibility of it.
This is the point of the post - there is a cost to "free" as we all know, and here is one good example. There's nothing wrong if a service is p2p, it should just tell you. Barring that, users of any "free" service ought to keep in mind that it might cost them in other ways.
(I suspect N is rather large)