They completely ignore the long tail benefits of building up a huge catalog. The streaming service with the biggest 'vault' wins, and yet they only seem to care about stuff actively in production.

Cancelling a story driven show early on not only pisses off fans, it effectively kills the whole value of the show for late adopters. Why would I start a show I know gets cancelled in season 2? If it had finished, people would work their way through the backlog. Owning a library of nothing but half finished shows is worse than useless for most people and further encourages people to cancel as soon as whatever current show they watch stops airing instead of sticking around to catch up on something else.