hampusw
WSGI applications can use a built-in HTTP server too (or FastCGI or ...). Node has an internal interface (similar to WSGI) for handing over requests to the web application and so on. That's not fundamentally different from WSGI. The main difference is that WSGI is a standard API, so there are several "WSGI servers" implementing the same thing (each of them similar to Node in some sense).
The same goes for other things, of course. You can't necessarily get unlimited outbound bandwidth and you can't buy an unlimited number of servers from them and so on... Sure, those limits (both quality and availability) aren't stated explicitly, but I still think it's fair to say that "whatever amount of inbound traffic you use we won't charge you for it". In extreme cases they will need to do something, but there are other options. There's a certain value in keeping things simple and flexible.
I do agree, though, that hiding (important) limits is generally not a good thing to do.