Do you have insights on what these API's make possible to do?
At a brief glance, it's to allow developers to add playback ability and access certain bits of user data for web and mobile apps and it does actually seem fairly prolific.
You could use it to create a personalized artist discovery app, for example, by tying into how Spotify determines artist relationships. Most people's use case would probably be accessing playlists for their website or whatever. It does look like it's possible to spit out a functional music player web app, as well. Furthermore, someone with a lot of time to waste could definitely devote that time to getting Spotify playback on MusicBee, but I can guarantee it would be a constant headache to maintain as a public release.
It seems that up until 2015, Spotify did sporadically support a
.NET library, but heavy emphasis on sporadically and again, like the web APIs, seems more trouble than it would be worth to try and jury rig MusicBee to work with. There is a
current library that wraps around the old library using Python, which is convenient for a lot of newer application purposes, but would make it even more of a " task" to incorporate with MusicBee.