GETPIVOTDATA formula usage

Hi,
After watching the EXCEL course, I would like to raise the following question:
When modifying the GETPIVOTDATA formula in order to make it dynamic within a P&L statement, why becomes necessary to copy+paste the year from the pivot table so that we can use it as a reference, instead using the year you already has as a title in the P&L table to be able to make the reference for the year?