Streaming is ephemeral. This is something TV fans realized in an abstract way about four years ago, when a boom of new streaming services led to more shows and movies playing licensing musical chairs. A documentary you like could be on Netflix or Hulu one month, only to disappear the next, later emerging on Max, Disney+, or somewhere else entirely. Tools like JustWatch, which keeps track of what's streaming where at any given moment, have become invaluable in recent years: It's simply too much for any one person to remember.

Despite the quickly normalized rotating catalogs, an unspoken social contract -- a promise that anything that a streamer boasted was "original and exclusive" would stay put -- still existed between streamers and subscribers until around 2022. Streamers may have quietly dumped some titles before this, but the practice made national news when Warner Bros. Discovery scrapped a reportedly nearly-completed movie and...