Spotify can argue that they allow it per user request and they do have control over their public API. And they exercise their option to block unwanted services to use their API. Shitty, but theoretically legal.
The service in question from OP is not using Spotify's API so no license applied. It sounds like they're automating/scraping, which in the US at least, was just ruled legal.[1] Of course, that puts scraper and scrapee into a leapfrog contest.
As OP points out, the best defense against customers leaving is to actually listen to them and please them. In this area, while Spotify might have a giant catalog, they are blatantly tormenting users by removing obvious, simple, features demanded by the thousands of votes on their forum.
As OP points out, the best defense against customers leaving is to actually listen to them and please them. In this area, while Spotify might have a giant catalog, they are blatantly tormenting users by removing obvious, simple, features demanded by the thousands of votes on their forum.
1. https://www.forbes.com/sites/emmawoollacott/2019/09/10/linke...