Netflix had “everything” because it was the first (commercially successful) mover on streaming, and as a result it was pretty much the only game in town for a long time. Every other producer HAD to be on Netflix if they wanted to reach the streaming audiences.
It was only after their success did all the other producers feel comfortable that this was the future, started building their own apps, and then had to wait for their exclusivity contracts they had given to Netflix expire.
There was a lot of fear around what would happen to Netflix when those contracts would expire, and that’s how we started getting their originals like Stranger Things.