Most people and even most companies don't need horizontal scaling. Hardware has been much faster and cheaper since Heroku's heyday. Scaling vertically with 80+ cores on a single CPU and 256gb+ of ram only costs a few hundred dollars a month these days. With caching on a server like that, it can handle a million requests a second, or tens of thousands a second for dynamic data from the database on the same server.
If Deno were supported on AWS Lambda I might think about using it. FaaS on a major infrastructure provider is what I need. I'm not putting a project that means anything to me on Deno's servers, they aren't really leading the industry and might not be around in the blink of an eye the way the tech world is going lately.