Scalability is probably a concern for a lot of people, but it still doesn't make it the point of the demo. They want to show that their service is capable of even running a workload so classically local and native as a full game with half-decent latency only using edge functions. And it's a mystery why you bring up streaming and CDNs. If you think that a 4K stream poses the same challenges as stateless, real-time, non-cacheable game engine processing targeting 60 req/s, then I don't know where to start.