They seemed to have recently removed it. The link below shows what it recently looked like.
The main issue was if you want to make a commercial app, there are no publicly available commercial terms, and it is easy for Spotify to not offer commercial terms to apps/companies that may in some way increase the chance of competition with Spotify. For example, if you wanted to make an app that would allow you to export your playlists, Spotify may offer you terrible commercial terms or none at all.
This is more restrictive than Apple.
https://www.iorad.com/player/2097656/Spotify---How-to-view-S...