Some might say that that was the result of the influence of al-Ghazali, a Persian scholar considered by many to be the second most influential Moslem after Mohammad himself. His being Persian was relevant, because Persia was VERY xenophobic, and he was no exception. He started out by being knowledgable in classic Greek texts, before deciding that any knowledge outside of the Koran and it’s commentaries was unnecessary, if not harmful to the Moslems. His influence spread out of Persia like a plague, and it was basically all downhill for the Mozzies since.
Yes some do say this. But the flaw in this reasoning is that mohamed himself was an even worse plague than Al-Ghazali.