I think most investors already are aware that almost half or even more of the crypto currencies are scam or not successful. Most of the ICOs I had seen in 2018 did not turned out great even reaching their hard cap in their sale. Given that, crowd funding companies now found a way to get more secure way of selling their coins through known exchanges or the IEOs.
yes IEO is a good choice at the moment and many are switching to using IEO, but that does not mean the ICO is dead if it is currently in a bad condition.
ICOs may need a process to grow better, so many people might give up so they are no longer at ICO, and he switches to the IEO.