Properties are only sacrificed during partitions. Due to Murphy's Law, if you assume partitions never happen they will happen more often but if you can tolerate partitions they happen really rarely.
There are plenty of systems that sacrifice consistency even while the network is fully connected, in the name of performance—for example, DNS, or any system with a caching proxy server.
Yeah, CAP is about the best possible behavior a system can have but you can always do worse.