Google always figures out how to scale products to millions and millions of users e.g. Search, Gmail, Google Maps, YouTube, Android. But I agree with you, they are not really innovating. I would say they are scaling software in order to make it useful for mass use.

That's basically how most successful large companies function. Acquire, optimize and scale. The specific areas they optimize and scale on differs by company.

But Google is so huge that they are only satisfied if they serve hundreds of millions or billions of users. For example if you have SaaS company you would be very happy to serve hundreds or thousands of customers but if your business model is advertising like Google's is then you indeed need millions and billions of users. Your motives and incentives change when you grow big and sometimes an average customer suffers. In this case people who loved Stadia in particular are left for dead because Stadia's growth didn't satisfy Google's apetite.