The Saints completely rebuilt the coaching staff, which in combination with ownership and management are the foundation of every team.
The coaching staff is one of the most significant rebuilds a team can make. Since there's no salary cap issues or roster limitations on the coaching staff, they can spend as much as they want and ad as many coaches as they want. For now, it looks like they've done a great job of rebuilding the coaching staff. Only time will tell if they did or didn't.
Regarding the roster, I don't think a demo and rebuild was necessary, wise or practical. I think the roster needed a remodel more than a rebuild. The Saints are remodeling the roster. Sure a lot of it looks the same, but they have already made some key changes and they still have the rest of free agency and the up coming draft to make even more changes.
Every public indication is that Moore is excited about Carr as his QB. You and others may not be, but Moore seems to be. Who do you think has a more informed and more complete evaluation of Carr, Moore or a fan posting on this site?