I think Guardians, in particular Guardians 2, was the test run to see if they can successfully expand the MCU on some galactic Star Wars shit.

They probably realized early on that they were fucking up with the Inhumans. If they had put that on the big screen instead of putting it on the small screen and immediately pulling the plug, it could have been the MCU's first major failure and had people thinking that the tide was turning for the worse.

Hopefully they know to keep it close to Guardians and Ragnarok. Thy have everyone thinking they can do no wrong (even when they give us Iron Man 3 and the Dark World) but they can easily take an L with The Eternals.