The main reasons ERC20. You know why ? Any body can simply deploy their token on ethereum network. Once a token deploy on ethereum network that's called ERC20.
So scammer easily deploy a token and build a website for distribution. After reach their target, just simply skip with money. Because for deploy token on ethereum there is no regulation.
There is no way to know scammer easily. Who is legit and who is scammer.
So once you joined any new ico, must check their existing business.
the point is we have to be careful in choosing ICO who really run the project developed, ICO is now a lot of use ethereum network because of the smart contract it has, there are only a few ICO who make their own network and sometimes even nobody interested when it is the thing which is good in the developers.
ERC 20 is now more famous than others and new players who want to enter will be difficult in the face of this
let's see what the future looks like.