As an investor, i cannot participate in IEO conducted by small and new exchanges. The main reason why IEOs are preferred to ICOs is because they are more prone to scam than ICOs, and this is because the exchange validates its legality with their reputation. Imagine Binance or any top exchange conducting a scam project, it will jeopardize their integrity, and these exchanges do not want their integrity in question, so they only offer legit and promising projects IEO. New exchanges do not have the reputation to validate a project, they are just after the profit, SO they might promote a scam project either intentionally or unintentionally.
New exchangers who organize IEO are usually to attract new customers. Exchangers are supposed to screen projects that will be promoted because they involve reputations. Small exchanger IEO is less attractive to investors, maybe because the liquidity is not large so the price cannot be raised when first listing