The article is simply incorrect when it says that Youtube Music doesn't allow streaming of one's own personal library. It does - up to 100,000 songs.
This functionality has been available since 2020, around the time when Google Play Music (which always had the ability to play from a personal library) got absorbed into Youtube Music.
This functionality has been available since 2020, around the time when Google Play Music (which always had the ability to play from a personal library) got absorbed into Youtube Music.
https://support.google.com/youtubemusic/answer/9716522?hl=en