The handling of the Inhumans has been a little strange.
Initially, there was going to be a phase three movie, but that kept getting delayed (I would guess that may be because they couldn't get the script right). As recently as last year, Feige said there would (may?) be a phase four Inhumans movie. If the show is a failure, a movie may not be a realistic option anymore because the brand of Inhumans may be too damaged.
If Feige never wanted to make an Inhumans movie, a failed TV show may be the perfect result for him.