I must be living on a different planet: What is described in the article and allegedly new and only possible with...

I must be living on a different planet: What is described in the article and allegedly new and only possible with Amazon's own music service is something I've been doing for a while with Spotify and an Echo Dot.

I can play music directly on the Dot and then on the phone switch that music to the phone - or I can do it the opposite way. This may not exactly be casting, because the music comes from the service, Spotify, not my phone, but the result is the same. (And Amazon Prime Music works the same way.)

This is actually pretty convenient, because I can switch music to the phone when I leave the house, so I can continue on earphones and when I get home I just switch back to the speaker.

So, am I missing something?
https://www.androidauthority.com/amazon-music-cast-alexa-889993/