Thanks!
Two things, mainly :
- To get the good ending the protagonist needs to use knowledge he learned in other timelines, so it wouldn't make sense narratively if it was just the player reloading.
- To beat all routes you'd have to know when to save, and make dozens of saves at the right time, figure out which save is which and which one you have to load, etc ... it would be very extremely hard and annoying. With the branching path flowchart this is way easier both to do and to understand.