I’d rather not get political but it’s purely inherited from politics, once you realize what Arabs did to the native Moroccan population during caliphate years you’ll know why.
Arabs are not and will never be native to Morocco, like I said, it’s like saying Argentina is an European country because they speak Spanish.
TL;DR Forced conversion and violence. (Arabs enslaved many Berbers and Arab leaders pretend this didn’t happen.)
My point is: Add Berber languages, don’t make Arabic the default language and separate Morocco from Middle East in statistics and such (MENA)