> Not least of which being that with bandcamp I can download purchased music years after purchase, even if artists have died or bands broken up, I wouldn't have that guarantee here

Note that this isn't guaranteed, especially for smaller bands that get picked up by a label. Most of the time the label just makes the releases hidden, so they're no longer displayed publicly, but can still be downloaded. However, some labels delete the release instead, so it's no longer downloadable from your collection.