They don't own Twitch. They didn't take any of the economic risk to start it. They're not on the hook for covering its server bills if revenue craters. If they wanted to put their money where their mouth is and buy a piece of the company proper, the current owners might be open to that, who knows.

But you don't typically get to run a company you didn't start, haven't invested a dime in, and can walk away from at any moment, unless you're willing to take on some of the risk. Risk is what gets you the rewards.