Under the "Your Music" section, there is "Songs," which lists every track whose big "+" button I've clicked.
There's also a "Local Files" tab which pulled in everything I've bought on the iTunes Store.
But I want to drag files from Local Files into Songs so that I can shuffle between both. Some of the tracks I've bought on iTunes Store aren't available on Spotify, so this would help supplement the library. I can drag the files from Local Files onto Songs, and a drag'n'drop icon appears (implying that I can copy them to Songs) but they don't appear there.
I know I can create a playlist and drag tracks to it from both Local Files and Songs. But then if I add more tracks to Songs, they won't automatically appear in the combined playlist. I literally want to be able to shuffle every possible track from Spotify and iTunes all in one go, and without constantly putting in effort to keep them synced up.
That would seem to be an obvious use case, given the strange absence of some pretty essential stuff from Spotify's library.
It would also be nice if Spotify didn't import podcasts and audiobooks from iTunes. It's a music app. There's no need for that. But that's a minor complaint.
EDIT: By the way, I'm posting this here instead of adding it as a feature request because I'm not entirely sure that there isn't a way to do it already. I've seen plenty of posts about Local Files that seem to imply this use case is already supported. But the language is rather vague.