there is no obligation because you get what you see, if people choose to see something apart from the reality that is their own fault. and because they are not companies, they are random people, most of them kids, releasing a token which you know is useless.
for example imagine an ICO token which is saying it is going to fix the energy problems, an ICO that is saying it is being used by medical sector for doctors and patients connecting to each other and having their information stored on the blockchain,.... (these are actual ICOs). then in reality all they do is that they create a useless token which will be traded on exchanges for a while and die eventually.
the team who gave all these promises will stop doing anything apart from coding the smart contract creating that token and going away as soon as they got paid.
this is the classic definition of being deceitful and performing a fraud.
Not to commit fraud is an obligation. Fraud gives ground to a civil claim too. As for the rest I was talking about moral obligations. Sofar.