First off, what exactly does "when one of the pistons looses pressure, drops, and ruins the cylinder" mean? Looses pressure = loses compression (I guess). Drops? How would a piston drop? I suppose the connecting rod could break, but that typically happens on the compression or exhaust stroke, sending the piston into the head. I guess it COULD fall back down into the pan after the connecting rod moves out of the way, but the piston 'dropping' wouldn't be the source of all the damage.
You may have to consider the source when reading reviews like that. Self-destructing engines are actually very rare, and can most often be attributed to abuse or neglect. Neglect includes having never changed a timing belt, which is a great way to do big $$ worth of damage to an engine when it breaks....if the engine is 'interference type'. Running engine oil past its useful life, or running the engine low on oil are other common causes of premature death. Overheating is another one. All of these can be prevented 99% of the time with good maintenance practices.
I have read horror stories about the MK1 Focus, but it related to stacks of recalls the car incurred during its growing pains period. I'm not at all familiar with stories of the engine committing suicide at 80K for no reason. Just about any modern engine can be good for 300K if it's well maintained and not abused.