It's a chicken and egg problem where there is not much point in building your own whizbang streaming platform and have no one come to it. Twitch is getting increasingly ad-nnoying and you can _ad_ barely _ad_ watch _ad_ it _ad_ an _ad_ ymore. That said that's still where you get the viewers and that's what people will pick. The ad-revenue sharing being the carrot here which will probably mean it's going to be success…
Or at least I was until they started interrupting streams in the middle of the action with no human input to show ads.
When the broadcaster clicks the ad button, it's a good time to run ads. They're probably taking a break anyway, there's nothing critical or even interesting happening, so watching some ads is fine.
But randomly interrupting in the middle of a conversation or right as the good part hits to show an ad shows that the Twitch management no longer understands or gives a shit about their platform.