They ended up using all kinds of things: Inhumans, time travel, Ghost Rider, all these things that nobody is using, and many times to great effect.
Then there was the division between Marvel TV and Marvel Cinematic on a corporate level.
So the showrunners, Jed and Mo and Jeff Bell, had to really scour parts of the Marvel universe that weren’t tied up with the incredibly elaborate plans of the cinematic [universe].
You know, no one ever knew the show would go 130-some episodes.