They are no longer sold new, but they didn't vanish from existence.
Personally I've found smartphones to suck awfully for playing music. Aside from having awful battery life, they lack tactile buttons and oftentimes the software sucks. I tried to put music on my phone and then found out it doesn't actually have a way to play music- so I download VLC and it manages to find about 20% of the music I put on, arbitrarily not allowing me to play others unless I navigate there manually for every single file. I still have no idea how to make playlists and can't be bothered to look into it due to the general deficiencies; If you are going to play music on a smartphone it seems the way you have to go is through the use of streaming services which is exactly what was noted in the article.
I still use a 16GB Sony MP3 Player for music. Which replaced a similar 4GB model I've had for 10 years. Only reason I replaced it was because it has literally fallen apart over time.