It's relevant since with both radio and streamed services the artist (or mostly the artist's label...) gets paid every time the song is listened to. With an MP3 you only count the number of downloads, not the number of times it's played.
This means that with downloads you get a rather crude measure of a song's popularity - you count the number of listeners instead of how often the song is actually played. It also means that a popular song will never stop being a source of income with a streaming service, as opposed to downloads where every user pays for the song only once.
About the privilege of selecting songs, according to the numbers in the article you pay 23 times (or maybe 12 times, it's a bit unclear) as much for being able to do so than you do if someone else selects the song for you.
Also, unless I'm mistaken it's the recoding's copyright owner - the label in most cases - that gets paid, and they in turn pay the artist. According to that other infographic, the artist gets about 15% of the amount the label gets.