They answer your question just two lines under the one you are quoting:

> For distributed systems over a “wide area,” it's generally viewed that partitions are inevitable, although not necessarily common. If you believe that partitions are inevitable, any distributed system must be prepared to forfeit either consistency (AP) or availability (CP), which is not a choice anyone wants to make. In fact, the original point of the CAP theorem was to get designers to take this tradeoff seriously. But there are two important caveats: First, you only need to forfeit consistency or availability during an actual partition, and even then there are many mitigations. Second, the actual theorem is about 100% availability; a more interesting discussion is about the tradeoffs involved to achieve realistic high availability.