They're all trying to have enough to watch to keep you subscribed all the time, which means they have an incentive to keep making more good shows. But there's no world where 5 streaming services will have something I'll want to watch every month, so it's pretty easy to just cancel until you've got a handful of shows to go through on that service. Then you subscribe for a month or two and come back later. That's way, way better than a local television monopoly like cable typically had, with channels you couldn't opt out of for a cheaper bill, that still forced commercials on you regardless of your exorbitant bill.