This is 100% amateur guesswork, but maybe the geography is part of the answer here? Norway is a bunch of extremely jagged coastline opening on to the fairly cold and empty North Sea, and most of the rest of it is equally jagged mountains, so it was probably easy for communities to be relatively isolated most of the time and therefore wind up speaking a little differently to the guys in the next fjord over. The Maghreb, on the other hand, is right on the Mediterranean, which has been one of humanity’s busiest and most travelled areas for thousands of years