Why do some people continue to say that the Arabs "fled Palestine" at the urging of their leaders when...?

It doesn't matter. They fled to avoid being caught in the middle of a combat situation. Probably both sides preferred to have as many civilians as possible out of potential war zones for the duration of hostilities. The Belgiums largely evacuated their country into Northern France prior to the U.S. invasion. The Germans made no attempt to discourage it. This is typical civilian behavior as war looms on the horizon; they hastily evacuate. It is entirely normal and it doesn't matter whether it was encouraged or by whom. The whole "issue" is simply used by Zionist historians to subtract attention from the real issue,which is the gross violation of international law and indeed all civilized norms in refusing to permit them to return to their homes at the conclusion of hostilities. Many Iraqis fled Iraq as the U.S. invasion became first imminent and then a fact. They have all been permitted to return. The U.S. -whatever it's crimes in Iraq - has not stooped so low as to prohibit their return and then bring over lower-income Americans to "settle" in former Iraqi homes with the intent of shifting the demography of Iraq from Iraqis to American expatriates. The whole mish-mash about who did or did not recommend short-term evacuation is simply a false "controversy" designed to obscure the real issue,which is: why were the Palestinians who evacuated from a potential war zone not permitted to return at the conclusion of hostilities? The answer is obvious: racism. You cannot convert a multi-ethnic society into a monocultural society without getting rid of all but one single "supreme" ethnic group to become the new Lords of the Land in an ethnocracy.