Budgeting in E1 8.12 - Why does system allow to change the budget after entering Approved Budget ?

We have plan to implement Budgeting in E1 8.12, TR 8.96.40

If we finalize the budget using Final Budget application, why does the system allow us to change the Requested and Approved budget.

Edit:

I read in the documentation:-

Using three cycles provides an informal audit trail. Because the system carries forward amounts to the next cycle, using more than one cycle might require little or no additional time.