And in trying to merely restructure you're also running the risk to carry over all pathologies, bad actors, "code debt", and general baggage, of the thing you're trying to restructure.
Yeah, I think this is why starting with a smaller part(s) of a big system that is more-or-less working and building on that is maybe the best we can do.
If only someone thought of this 240 years ago when some peeps got frustrated enough with their government to fight their way through a separation from that government.
Choices...