You've just made me realise that the universe itself is only eventually consistent - that's what all those weird quantum observer / wavefunction collapse events are.
Everything's eventually consistent on an ever-present sphere around the incident expanding at the speed of light. No faster.
Even if the sun were to blink out of existence, we'd have 8 minutes that we wouldn't know. Gravity would still be there, holding Earth in place. The light would still warm us. Then 500 seconds later, darkness. We'd be flung out on a tangential course.
It's important to not overstate the importance of that bound, though.
Of course, a single machine guarantees there can be no partitioning, and really easy to obtain consensus. It might not be terribly fault-tolerant, however.
(Briefly, note that the original article is critiquing that definition of availability in practice which is legitimate but not relevant to this sub-thread.)
What I'm saying is that EC is most definitely NOT a requirement of physics/the speed of light (what your original post claimed.) The speed of light only sets a (theoretical) limits on how fast you can implement a consistent system.
The original Paxos paper ("The part-time parliament") uses an analogy of a quorum of parliamentarians occasionally getting together in the the same building and agreeing on something. Of course it being the same building is arbitrary and doesn't actually matter, but it's easier to intuit that the speed of light isn't an insurmountable road-block at that scale.
CA is the correct way to understand a single un-replicated DB instance. And it's really really wrong :)