Viral marketing is a byproduct of multiplatform releases. You're able to generate more buzz when a larger percentage of gamers can play your game.
Have you seen what the top selling games are every year? It's all multiplatform releases. These companies are moving away from platform exclusivity because it so obviously doesn't work.
Because as the plastic box diminishes in value, a phenomenon that's occurring before our very eyes, the game as a platform is rising.
What you must realize is that GAAS is relatively new in the gaming space. To be so new, and to take over the industry so quickly, with such little investment up to this point...yeah, the dominoes are going to continue to fall in the direction they're falling.
Btw, did you know that that PlayStation Network gets about 100 - 120 million MAU? Did you know Fortnite alone has over 100 MAU? Minecraft has over 160 million MAU.
Games are the platform, not plastic boxes. The power has shifted dramatically over the last 10 years.