And because governments really don't want to admit to their constituents how much they really spend and what they spend it on, the rules are ... less than perfect.
But a blockchain can vouch for the fact that the ledger was made according to the (supposed to be published and fair) rules, and that the rules didn't change except with total agreement.
So enron would have been able to book things in against the rules, but an easily written automated program would have detected such shenanigans, and there would not be anything Enron could do to prevent that program from raising red flags when the transactions don't follow the rules (so it would not be possible to book in such transactions, then not book in payment in full when it's due. If you're wondering how that's possible, consider that in bitcoin there just isn't any credit. So the only way to place an order using a bitcoin directly is to stake they money ahead of time, optionally with an instruction that it'd be paid back if an "oracle" (anyone else on the blockchain) says it's not delivered correctly)