I think you're going out of your way to connect the dots with these movies. And I love Kill List. That is basically 3 different movies wrapped in one. Midsommar is one film from start to finish without misleading the viewer about where the story is about to go.
Kill list pulls the okey doke twice to set up the third act.
I could connect a lot of other dots in this movie to other films without calling it a ripoff. Consider my post before with the tweet showing that shyt hidden in the background of his scene. I could argue that he jacked that from Kubrick and what he did with films like Eyes Wide Shut...
Is Midsommar a ripoff of Eyes Wide Shut? Hell no. Good artists in any genre take influences from people that influence them and introduce them into a their own tapestry.
That's some shyt I took away from an interview in Slam magazine with Stephon Marbury. They asked him what he did to tweak his game each off season and he said he studied the game of different players so he could adapt their moves into his own repertoire.
Does that make some a plagiarist? Up for you to decide
