I think any potential customers would understand that scaling isn't the point of the demo. It's unreasonable to assume that they'd infinitely scale a processing- and bandwidth-hog like this just for fun.
As a potential customer, scalability is definitely top of mind. If you can't scale a tech demo, then I'm not left with a good impression with a CDN which is supposed to handle millions of requests per second.
It's not like Doom is that intensive, and the the bandwidth is certainly less than a single 4K stream!
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.