[Gibbon]

The article assumes that older releases are unavailable due to laziness. This is not always the case.

Recordings can be deleted for any number of reasons including: infighting, copyright issues, legal issues, embarrassment, ego, lack of interest, changing trends.. you name it.

In some cases the rights, once sold to a label, can exchange hands so many times, that ownership can't even be determined.

In particular, if any of the affected parties go out of business, the songs can end up in limbo for eternity.