Well, IEO is part of an exchange strategy of making money, it's equally a way of building some confidence in crowdfunding as it helps to minimize the risk of fake teams and shitty projects. We this IEO stand the test of time? No, because scammers have already started taking advantage of some smaller exchanges to bring shitty projects. It's wise to buy from a reputabel exchange and cross check any project conducting IEO.
I think scammers are inevitable. Even with this IEO innovation, it is not easy to just invest. the biggest exchange market started this crowd funding but even them can not insure at how much and when the profit would come.