I like 0MQ a lot, but this is disingenuous. Let's break it down:
> portability
Sockets are just as portable, more so on UNIX descendants where one can rely on relatively consistent socket APIs. Beyond that, almost every single language and runtime (Python, Ruby, Java, OCaml ...) provides a portable socket API.
> message framing
Length-prefixed message framing winds up being 10-100 lines of code in almost any language/environment.
> super fast asynchronous I/O
Sockets have this.
> queuing
Sockets have buffers. The OS can use those buffers to implement flow control. This isn't the same as queueing, but the truth is that you rarely want blind background queueing of an indefinite number of messages that may or may not be delivered.
> support for every bloody language anyone cares about
Just like sockets.
> huge community
I don't think you can get 'huger' than the community around sockets.
> price tag of zero
Seeing as socket libraries ship with everything, does that mean they have a time/resource cost of less than zero?
> mind-blowing performance
Also, sockets.
> protection from memory overflows
This has essentially nothing to do with a networking library. Plenty of environments have safe/efficient zero-copy chained byte buffer implementations/libraries.
> loads of internal consistency checks
Library correctness isn't a unique feature.
> patterns like pub/sub and request/reply, batching
Ah-ha! Here finally we get to the meat of it!
If you need QUEUES, including pub-sub, fanout, or any other QUEUE-based messaging structure, than 0MQ is better than sockets!
> and seamless support for inter-thread transport as well as TCP and multicast
Inter-thread transport of already-serialized messages at the transport protocol layer doesn't make a ton of sense from an efficiency perspective.
> ZEROMQ IS JUST SOCKETS
No, 0MQ is a lightweight network message queue protocol. It's not competing with sockets.