I know that this is meant to mean: in the real world you cannot just write off partition resilience and still call your system highly available, since partitions will happen sooner or later and when they do your CA system won't be available.

But in the other hand, having a system that is always available _except_ during a network partition is a useful thing: you can design a network where partitions happen much rarely that the rate at which individual machines die.

I.e. in practice a single node, while if you nitpick is the only true CA, will available for less time in average than a multi node CA system which if you nitpick is not CA (provided that the underlying network is partition resilient; it's not a boolean, it's a probability)

(See Google spanner)