I agree that the defi hype is very similar to the ICO and IEO hype, but I think there is more to it. Yes, of course, there are a lot of scams among defi projects, but some are really very useful for cryptocurrency. By the way, IEO is still popular today and will always be popular.
Of course some are helpful while some are not, like an IEO or ICO, not all projects are really useful and in fact we can only count the projects that has really survive until now, some just show up for a while and gone forever.