Zeromq is just a bit of sugar on top of tcp sockets. It isn't a message queue or anything close. You would be wasting a ton of time reimplementing a lot of basic features like retries, persistence, service discovery, dead letter queues, priority, and a ton of other stuff.
Basically, one is decentralized and you can set up a massively parallel architecture, with eg each topic or subthread having its own pubsub.
The other is a monolithic centralized pubsub architecture.
You could argue that git in large institutional projects converges to a monolithic repo so at that point it’s less efficient even than svn.
But for most use cases, ZeroMQ would allow far more flexible distributed systems topologies and solutions. No?
Edit: HN and Google are both awesome: https://news.ycombinator.com/item?id=9634925