Earlier quoted context omitted.
Another point of data in favor of "they deleted my music" here. And when they did it, they were only matching on the file metadata, so the album they removed was truly lost, since I got some weird techno album in its place. Thankfully, it's one I can recover from a CD, when I find it again.
All ethics of the deletion aside, matching on metadata is a weird, crappy approach (and that itself is pretty consistent with my other experiences with iTunes). It shouldn't be hard to imagine that metadata will have collisions, and include something like a hash of the actual data.
Intentionally or not, history (what songs actually were on an album) gets edited unless you manage music files yourself.
(The Apple behavior described in the article is way worse than what Spotify does, of course.)