AMQP, JMS, Kafka, and MQTT get lined up as if you pick one and move on. Most of the time, that comparison is a category error.That error is getting easier to make, because the tools now overlap more than they used to. Kafka added queue semantics with Share Groups. RabbitMQ added a log. AMQP's standards committee reconvened after years of quiet, now around agentic AI. MQTT settled into version 5.0 as the default at the edge. JMS, the mature exception, sits still because it already works. The tools are borrowing each other's features. The models underneath, and the trade-offs that come with them, have not merged.