As a systems engineer you probably also know that building something complex from the ground up will have very buggy rollouts for the first versions :). Rewrites also have a pretty good history of bankrupting organizations. The current system is very fixable if somebody actually had the political will. Compared to building something new it will be easy.
This reminds me of the discussion about terraforming Mars. It’s deemed to be too hard and expensive to reduce our greenhouse emissions on a perfectly fine planet like earth so people think it’s easier to terraform a barren planet.