This does not make your statement wrong, but there are several other dependencies that do not allow this to be generalized.
Minecraft is linked to the growth of many Youtubers because its the most open game you can find and thus giving creators the biggest canvas to their imagination. It's like saying that 90% of a piece of art is the used material... It just doesn't make sense.
So it highly depends on your Audience. If you are a variety streamer, your audience is used to the changing environment. However this does not apply to the vast majority. If changes in audience(game) can cause up to 90+% difference its hard to quantify it as negligible factor.
Not at all. There are so many small Fortnite streamers because they want to become big like the popular ones and they know it is extremely hard to grow a stream out of the top 10-20 most watched games.
You can easily prove this: pick any popular but-not-so-much game and you will find way, way less streamers. To the point some have only 5-10 people streaming it, while having many tens of thousands of concurrent players. And yet only a total 100-1000 viewers combined are watching at a given time.
If you are good enough, people will buy your next album/book in the same genre. If you have a cult following, people will buy your next book/album in whatever genre.
This argument is flawed because 1) many streamers do exactly that, and 2) just because a streamer is not interesting when he's not playing a game doesn't mean that all the value is coming from the game. A juggler is not interesting without balls, does that mean it's the balls providing 90% of the value?
Given that:
* many streamers spend a substantial amount of their time just sitting and chatting with viewers, no game being played.
* if it was the game providing the value, you could just show a recorded playthrough without a streamer there to interact with the viewers, but this is not very popular.
* many streamers can play any game at all and draw a large viewership, but there are no games that any person can just start streaming and easily draw a large viewership
It seems fairly clear to me that the streamer contributes much more value to a livestream than the game being played.
A good example of this is DayZ, a game that was very buggy and had a lot of negative criticism, and yet it became very popular because streamers pushed it so hard. Even bugs and broken mechanics can be fun if you are watching streamers laugh at it
You could also consider the game to be a “set,” i.e. a digital space that the livestream is filmed within.