It feels more like "I already pay for Netflix, so why do I have to pay anyone else for content Netflix doesn't have?" That's a bit like asking why you should pay for CNN and HBO. Basic cable should come with ALL the content, right?
I am not saying the content providers owe anyone a streaming option. But grandparent is right about path of least resistance.
Cable would force OP to buy 37 useless channels whose content is being subsidized by people paying for the 5 channels they actually watch.
OP was right, streaming services are fractured and disjointed right now and nobody offers everything. Netflix has shifted primarily to their own content and increasingly only carries independent and foreign films and shows. Hulu is an ad packed disaster area on top of having a horrible streaming experience on current content designed to try to prop up the failing cable subscription model. Amazon is the best bet for most other content but is of course the most expensive of all the options since it isn't a proper subscription service like Netflix or Hulu but instead more closely emulates the Blockbuster Video model of old. None of the options is a really fully satisfying replacement for a cable TV subscription, but each is just good enough that it's still better than cable TV. In aggregate, the experience is definitely the best option, but it's still really frustrating (not to mention expensive) to constantly need to juggle between the three major services (and the dozens of smaller ones) in order to access the content you want when you want it.
Yeah. They don't have everything I want to watch, but they have enough decent stuff that I find something interesting easily enough.
I am slightly cheesed when something I was watching was taken off before I finished it... I understand why they don't advertise when they'll loose the rights to a particular show, but I'd sure like some way to know how long some shows will be available.