e.g. When you pull up an auto-generated playlist or look at recommended suggestions, are you just looking at content which the provider prefers to show you? Can you trust reviews from the same company that's selling you the content? If some content isn't on there, will it just disappear into the abyss? If the provider decides to drop some content, will you ever see it again?
And yes, if content isn't on Spotify for me, it basically doesn't exist. If it's on Bandcamp maybe I will download it.
Spotify allows you to see songs that you have added that have been removed from availability as greyed-out names.