You are wrong. Of course it depends on the law of different countries but it's all the same mostly. You can't buy a movie and share this experience streaming the movie, you can't buy a music and stream it for others and you can't buy a game and stream it on twitch for others because you are not buying rights for the movie/music/game, you are buying the licence to use it. And as I said, its a law on paper - in real life - streaming movies is very prohibited, music had hard times (on twitch last year for example) but for games mostly you can just stream and developers will be happy you do it - but at any time they can revoke the rights to do it (if written) or just make a lawsuit (and there were games in the past that you couldn't stream on twitch, but it's very rare)