A serious Spotify problem, shared with other services, is how poorly duplicate versions of songs and albums are managed. There are many different (re)releases of what is apparently the same album. Also, the same song can appear in many different albums/compilations. Spotify largely fails to understand all these different versions of albums and songs as being duplicates. Meaning that:
Existing features do not work reliably
Disliking / Blocking songs
Exploring the music catalog
Song popularity indicators
Skipping duplicates when adding songs to playlists
Proposed features will not work reliably
Tagging songs and creating dynamic playlists
Song play counts
Alternate modes for Discover Weekly, Radios and other discovery features
Show and play only not-played songs
Show and play only not-liked songs
Comparing libraries between friends
More detailed problem descriptions:
Songs I have liked are often not liked within any album with the same name on the artist page, nor within the list of top songs on the artist, nor radios I play, nor my own playlists. Making me add it again and again ending up with tons of duplicate liked songs.
Albums I have liked are often not liked on the artist page (Same exact album name)
Albums and Album-Songs that I liked on the Artist page are no longer liked when I look at the Artist page a(day, week, month, year) later because the album displayed on the Artist page has been replaced by a new version.
The same song turns up again and again in top songs for an artist
Duplicates of disliked/blocked songs keep playing, turning disliking/blocking songs into a game of whack-a-mole.
Often the songs in top songs, or radios/playlists, for an artist are not from any of the album versions visible on the artist, but rather links to some some sort of zombie album release not accessible in any way except through the link from the song. So I like a number of top songs or radio songs for an artist and minutes later view the same songs in an album with the same name as the song I liked but this one is not liked.
Avoiding duplicates in playlists does not work reliably. So I have playlists full of duplicates.
The above problems mean I end up with a ton of duplicates in my liked songs. And thus, when I add songs to playlists by selecting all liked songs from an album/artist or similar the playlist ends up with duplicate songs
Spotify badly needs to implement a strategy for handling this, such as making one version per album and song preferred and making sure that their interface consistently use these preferred versions everywhere by default, automatically migrating all a users Liked songs and playlist songs to this version whenever it changes. The user should only need to see this horrible mess if they want some very specific version of an album/song. Then some way of opening the doors to this pandora's box can be provided. Like a "See all releases" link when you open the preferred version of an album or song. Combined, perhaps, with the option to lock liked songs and playlist songs to this specific version.
However, it is a huge burden for a company to manage this data and the choices made may be controversial. This is likely to be why it is still not fixed even though doubtlessly Spotify is well aware of just how big a problem this is.
For a single company managing this data is prohibitively expensive, for the community of tens of millions of users doing so is a trivially small amount of effort. So here's my suggested solution to all these problems:Crowdsource it. Let the users mark different versions of albums and songs as duplicates of each other and possibly vote for which one should be the preferred version. The user would simply paste in the links to other songs or albums into a "Report duplicate" function on a song or album. This would remove the immense burden of managing this data from Spotify employees and, if voting is implemented, makes it very hard for users to complain about which version is preferred. It would be a democratic process among all the users.
I think that solving this problem first could be a huge competitive advantage. I have already posted this as a suggestion to Tidal as well. Please get moving on this Spotify if you think it a good idea, or you might miss the boat.