Also partition in the system definition can be as little as 'single node failure'. But I've seen plenty of systems that handle single node failure, but really

Also partition in the system definition can be as little as 'single node failure'. But I've seen plenty of systems that handle single node failure, but really get fucked when you have a network split where 50% of the nodes can talk to each other but not the other 50%. CAP theorem doesn't help you build a system that doesn't do very bad things when this happens.