I'm assuming Netflix's core KPI would be net subscriber count, and everything that Netflix does, in some form, would be driven by that.

Going further, I'm guessing that there are (or will be) some shows that show highly rated but producing more seasons would not draw in new subscribers or decrease retention rate. It might be that there are shows where their data shows that a large percentage of the fans of that show are unlikely to cancel their subscription, in the case that new season is not produced, and that a new season will not be the kind-of thing that will create new subscribers.

If wonder if Science Fiction might be a genre where the fans are unlikely to cancel their Netflix subscription, but a multi-season run in also unlikely to appeal to people that don't already subscribe to Netflix.