Why put a Media Player in a History Graph

I’m really feeling like I’m missing something very fundamental. On the page https://www.home-assistant.io/lovelace/history-graph/, the example is given of

- type: history-graph
  title: 'My Graph'
  entities:
    - sensor.outside_temperature
    - entity: media_player.lounge_room
      name: Main player

Why would you want to put a media player in a history graph? What’s the connection between the media player and the outside temperature? Are the y just two examples of something which can coexist in the same graph?

The example shows that you can have multiple graphs under a single history-graph card. The card will show two different graphs, one for the media player, the other for the temperature.

I’ve just realised that the same example is used in a lot of the cards. Thanks.