I don't claim this is a complete answer but contrast broadcast and streaming.
BROADCAST: Pay for pilots. Pick up some of them. You know a good chunk of shows won't make it past S1. Some won't make it that far. But, especially pre-reality show, you still have a schedule to fill with scripted TV. So you throw a bunch of mostly economical stuff at the wall and see what sticks. The stuff that does, you pick up and groom it.
STREAMING: Same deal with pilots. But now your main objective is to find that hit which will net you a bunch of new subscribers. Yeah, you need filler too but that's not as big a deal. So you're probably incentivized to do more swinging at the fences. And you probably don't care about having as many slow burn series because it's all about how many new subscribers you can sign on and, especially with serialized TV (which streaming/internet has also helped enable), if you don't grab people up-front, it's probably a waste.
BROADCAST: Pay for pilots. Pick up some of them. You know a good chunk of shows won't make it past S1. Some won't make it that far. But, especially pre-reality show, you still have a schedule to fill with scripted TV. So you throw a bunch of mostly economical stuff at the wall and see what sticks. The stuff that does, you pick up and groom it.
STREAMING: Same deal with pilots. But now your main objective is to find that hit which will net you a bunch of new subscribers. Yeah, you need filler too but that's not as big a deal. So you're probably incentivized to do more swinging at the fences. And you probably don't care about having as many slow burn series because it's all about how many new subscribers you can sign on and, especially with serialized TV (which streaming/internet has also helped enable), if you don't grab people up-front, it's probably a waste.