I think I see what he's trying to say, but there's a letter that isn't included in the adjective "CA", and that letter is "P". How could it be otherwise? Indeed, from TFA: "Kafka can do this because LinkedIn’s brokers run in a datacenter, where partitions are rare."
You're correct, the system does not advertise partition tolerance, and @Aphyr does indeed confirm that the system is not partition tolerant.
Broadly, I think sacrificing P is pretty deeply misguided. If you run a distributed system at any scale for any period of time, you're going to experience network partitions, even within a single DC. (I speak from experience: I work on a distributed system which runs a whole bunch of machines in a whole bunch of datacentres worldwide. We see a reasonable number of non-trivial within-DC network partitions every year.)
Partitions are != network partitions. Processes on the same node can become partitioned, threads in the same process can become partitioned. Actors within threads can become partitioned from themselves or other actors.
In my experience network partitions are not the most common kind of partition although they are well represented, especially on some network topologies.
IMO you should never assume that any two things won't be partitioned as part of your expectation of correctness or availability.
Can you describe a partition of two actors within the same thread? I'd guess this would be in some sort of logic failure state, where either the consuming actor doesn't correctly receive its messages, or the producing actor doesn't correctly transmit.
