Netflix got there fustest with the mostest, in the apocryphal words of a Civil War general. Its dominance of the streaming entertainment business is reflected in its market cap, which rose 15-fold, to more than $150 billion, in eight years. But a line in its latest earnings report was a stunner: Its U.S. subscribers actually dropped in the second quarter.

More Americans left the service than signed up. Wow.

Netflix...