Cirno actually got big off Dark Souls speedruns, since there was a market for Dark Souls gameplay with little commentary. Twitch always demonstrates the power of consistently providing something day in day out. On the OOT side, Clint Stevens has several thousand consistent viewers after doing 100% runs for hours every day for several years, and capping out at 2nd place. Autists love consistency.
To be clear, Cirno is now very much a variety/weeb streamer, and Clint recently burnt out entirely after trying to switch to Mario 64 and appears to be back, but he's lost the consistency and just streams whatever. He's got a completely different core community now, but similar numbers.