From inception, IEO has proven to more effective than ICO I guess part of this is because exchanges hosts IEO. But recently there has been a decline and in comes scam exchanges with fake everything including fake buyers. This has also made investors lose a lot of money with the wave of new projects out there right now
Actually it is almost the same as before when there were still many good ICOs and IEOs had not yet been born, now when IEOs were born and many were good, this was also used by scammers to get money from investors, the same as now where there are many projects. The DeFi is fake and it's the work of the past con artists too.