The main reasons why cryptocurrency investors prefer investing in IDO, and not IEO are accessibility and security. Availability, since anyone can buy tokens during IDO with any amount on hands and at the same time you do not need to undergo any additional checks. Besides, there are no jurisdictional restrictions in the Initial Dex Offering for investors, while in the Initial Exchange Offering they may be present.
With regard to security, in the case of IDO, the investor should not transfer his funds to the internal accounts of the exchange. All transactions are carried out through smart contracts that provide p2p transfers. DEX acts here only as a provider of these smart contracts. The platform does not store user's money, private keys, or other important confidential data.
In addition, IDO stands for decentralized finance. In the world of cryptocurrencies and blockchain, such projects enjoy significantly more support than projects that are under the full control of companies or banks.