Why does Netflix care how the movies they stream to you are consumed? Shouldn't your $8/mo allow you to stream any movie to OpenFlix and consume however you like?
Unironically, you should. In a more just world, laws would mandate service providers not obstruct third party clients.
You are also not allowed to show these Netflix movies on a big screen in front of your house and charge people. The 8 dollar are for a specific use case, just like the tokens in the subscription.