I think some people may not know the full meaning of STO. It's called Security Token Offering, which means it is only meant for security tokens. While ICO can accommodate security tokens, utility tokens, equity and so on.
The fact that we are in a system decentralization in the crypto space, which so many crypto enthusiasts prefer. Whereas STO is centralized. Which means tje lovers of decentralization would prefer ICO.
In order not to fall victim of scam, investors just need to take to precautions.
Security tokens don't actually fall under ICOs. That's part of why a lot of ICOs are facing issues with regulators because their "utility tokens" should actually be labeled as a security.