No Manual Backup
That fine science fiction writer, Robert A. Heinlein, wrote in "The Moon's A Harsh Mistress" of the utter stupidity of controlling everything from transport to environment to writing paychecks using one large computer system, with no manual reversion or as he called it, the possibility of "jury-rigging" while a problem was solved: because "if it can go wrong, it will".
He'd have been interested in this present discussion.
R