I think that Streamers should be able to choose up to two categories at a time. For me personally, this would mean being able to choose both the ASMR category as well as the Stardew Valley category, as my stream is both of these things. Another example would be people who play retro games. They would be able to categorize their streams as both Retro and whatever game they may be playing.
This way, you wouldn't have to sacrifice exposure by picking between two possible categories. There are games that people play that do not have a lot of followers. Indie games hardly ever get noticed. So those who play the small games never get the exposure. So having an Indie game category could group them together, giving more exposure, but then you could also specify the game so that those few people who are interested in the specific game can find it too.