[Benvie]

The important bit is that this is THE core abstraction used in node and the node community. If for no other reason, you should do it (if you're using node) because it's how you hook into the existing libraries.

The main benefit here isn't that it's possible to do this thing, as many people pointed out the myriad ways this is accomplished elsewhere. The key point is that everything that manipulates data, node core as well as the userland libraries, implement the same interface.

[sirclueless]

That's not really true. Most libraries expose a callback mechanism, where the result of some IO is passed as a Javascript primitive to a callback function that you provide. The Dumply guys used to use an API like that.

The notion of piping the output from some I/O (say, a request to S3) into the input of some other I/O (say, a currently writing HTML response) without ever referencing it is blessed by node, which has a stream type as part of its standard library. But it's far from the most common abstraction of asynchronous work.