A friend said they fade away with time as some are based on IEO and some use IDO but as time goes by they faded away, is this true?
yes that's absolutely true. launchpad will eventually be deprecated as well, and there will be a new way to raise seed funding. Initially launchpad was expected to prevent fraud and verify new projects. but the truth is there are still a lot of shit projects out there. they use IEO/IDO on the launchpad platform with ease, even I doubt if every project is verified before starting to raise funding. because of this, launchpad will be deprecated later.