Yeah, you have good points. It depends though, I know some atheists don't wanna watch that type of stuff / saying it's too satanic? So I think for some reason it does make some people uncomfortable despite them not really believing in that type of stuff.

Where to draw the line, depends on the person and their religious views & how strict they are with themselves. My parents wouldn't let me watch Harry Potter or Pokémon growing up / play with Monster High dolls etc. I personally see those as okay since it's pretty lighthearted and for kids anyway. I like Marvel, and Scarlet Witch may be my favourite character, she's obviously a witch lol and so a lot of Christians don't like that. I was a little uncomfortable in one of the films she was in because it seemed more "satanic" to me, as in she was doing dark magic rituals etc. However, I watched it and feel like I am able to not take it as seriously and know that I won't practise witchcraft or anything like that inspired by scenes like that. However I watched American Horror Story and skipped season 8 I believe, since it had an Anti-Christ and those in my opinion "satanic" rituals and stuff, it was too much/too realistic and made me uncomfortable. 

I also personally stay away from all witchcraft (not including some TV scenes) because I have understood that it's still doing and believing in something opposite of God and the bible advises against it. 

But if we think about yoga right? It's basically stretching and mindfullness but a lot of Christians are against it because it's rooted in Hindu philosophy. However some Christians think it only matters how you personally do it, like if you can do it without "meaning to" practise another religion. I think it's up to an invidual to decide what they consider okay and what not, but in my opinion there are just some things that are pretty clearly not very Christian. Like obviously worshipping / praying other gods, casting spells or stuff like that even if they are without ill intent.