In ~2008 Netflix delivered DVDs by post, and the only people getting their video online were pirates and anime fans. So when Netflix approached Starz to license streaming rights nobody else wanted them, and Netflix got a great price for loads of content like recent Hollywood movies. Allowing them to offer a huge catalogue to US viewers for $10/month.
By 2012, when the contract came up for renegotiation, Hollywood had worked out that streaming rights were big business - and they figured their output was worth way more than $10/month. There were $100/month cable packages that got you less than you got from a $10/month netflix membership, that's a lot of money left on the table - so of course the deal didn't get renewed.
And Netflix has never been the same since.
[1] https://money.cnn.com/2012/02/29/technology/netflix_starz/in...