Along with the sale method it also ensure that the coin will be listed on that particular exchange and will be traded there immediately after the end of the sale. So none of the developer will run away without listing on any exchange. In the previous year many developers collected money from the ICOs and escape away with not any listing. This issue is now solved with the IEOs. The other issue was the developers were promising for some exchanges during the time of sale and after the end of the sale they were not going to list there, so now with IEO you will find from the beginning that where we will trade the coin.