According to Islam, *all* borders are illegitimate and peace will only be established once they're completely eliminated under an all-conquering Mahdi. Actual Muslims, however, are extremely tribal and nationalistic - both in the Near East and North Africa. I don't think it's escaped the notice of foreigners recruited by ISIS that they tend to get the scut jobs - i.e. be assigned suicide bombings. Rebellions tend to fizzle out because the leaders can never agree on who gets to be boss (and gets the associated perks), and spend a lot of time fighting each other, whereas the powers-that-be have already worked it out, meaning they act with one voice.