The main difference as I see it between going totally off plan for a day or two and maintainance is that with going off plan, you are (usually) drastically increasing your carb amount from one day to the next. That's a big shock to your system that has gotten accustomed to much less carbs and part of that is water weight gain as your glycogen stores are replenished all in one huge shot of carbs.
With maintainance, you work your way towards it gradually increasing your carbs a you go instead of making one big jump all at once. This allows your body to gradually readapt to the higher carb levels and also allows you to find out what your maximum level without gaining is as well as discovering what higher carb foods trigger cravings and which don't.
All that is one very good reason to not stay on induction until you get to your goal weight; if you do, you won't have any idea how to maintain that loss once you get there or it will certainly be more of a struggle than if you had worked through all 3 phases before you got to goal.