"After signing in to your Facebook account in Spotify’s desktop app, you could then send and receive messages without ever leaving the app. Our API provided par

"After signing in to your Facebook account in Spotify’s desktop app, you could then send and receive messages without ever leaving the app. Our API provided partners with access to the person’s messages in order to power this type of feature." > This is a write permission. So you needed to give Spotify permission to create a message. It seems that your system combines the read and write permissions, since you just grouped them together by saying "access to the person's messages". How is it a write permission when the thing you quoted says "send and receive messages"? That's an inbox. An inbox reads messages.