I'm not exactly sure why it assumes such primary use case though. There are many downsides to such a scenario: playlists are not searchable; their order is also fixed, which exacerbates the former problem when your playlists grow massive. From my understanding of the UI, the user's library is supposed to solve both issues, but it is not easily browsable on either iOS or Android (my unfortunate choices for consuming music). Perhaps, a workaround is to have "smart playlists" or optional tags for an album that you can come back to later.
It becomes a bit frustrating because basically the only way to listen to an album is to search for it. I'm mostly OK with that workaround, but the problem is that many albums have duplicates. I specifically select particular tracks I want in the library to make sure I can maintain consecutive playback of entire albums that do require it; a selection process which is rendered useless when re-doing the search from ground up on the go.
It becomes a bit frustrating because basically the only way to listen to an album is to search for it. I'm mostly OK with that workaround, but the problem is that many albums have duplicates. I specifically select particular tracks I want in the library to make sure I can maintain consecutive playback of entire albums that do require it; a selection process which is rendered useless when re-doing the search from ground up on the go.