Scragged sectors are a risk, but not the main risk, of power drops. What's worse is blocks still in buffer RAM on the drive that the system thought were already physically on disk, because the drive told it so.
When the drives lie to the file system, the file system can't guarantee anything. Most drives (i.e. the ones you have) lie. Drives that don't lie cost way more, and are slower; it's much cheaper to add some battery backup, and even some redundancy, than to buy the expensive drives. There's no point in discussing fine points of data ordering if you haven't got one or the other.