Yes, you are right the successful IEO's are from the potential exchanges like Binance, Kucoin, Bittrex, Okex etc. Of course, IEO's already listed on those exchange cannot able to increase their value but only from the Binance those coins has given very good profit to the investors.
Let us not presume that any IEO that comes from Binance will always give profit to investors in short term as it's not true.
Some people doesn't know the real IEO success rate of Binance when they see one project successful they tend to think that all the projects will be a success and that's why the hype starts.
which is not true sucess of the project will not be base which exchange that project listed . the project will be successful if tthey continue to make solution and develop thier project to the real goal of it .