To be able to make different content without the algorithm screwing them over because of the lower views

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It makes sense. I like the way peer tube does it, where your account is not tied to a channel, so you can have as many as you want and have them all associated with your main account.

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The youtube algorithm strongly favors returning views, if you have a channel that has 3 different types of content you run the risk of having little overlap between viewers of each type. Youtube sees this and thinks you’re content isn’t good enough for most of your viewers to reliably be interested in your channel and you get lower recommendation rates and promotion in the algorithm.

So youtubers opt to have multiple channels for different types of content to they have a better returning viewer rates.