RNAV approach DCT to IF
For an RNAV (GNSS) approach Airbus says that "direct to" clearances to the IF may be accepted provided the resulting track change at the IF does not exceed 45°.
I've seen some approaches where, if you fly the whole approach starting at the IAF, the track change at the IF is close to 90°. What's the reason then that we can't accept a direct to if it's more than 45°?