The presence or absence of albums and songs in Spotify is almost always decided by the artist or label. Sometimes there are changes in licensing, sometimes agreements cannot be reached, there are many reasons why some content is not available.
You can try contacting the artists about whether they plan to be on Spotify as well as give a like to this Wishbox idea. :)
Hope this helps!
SebastyRock Star 15
Help others find this answer and click "Accept as Solution".
If you appreciate my answer, maybe give me a Like.