There are sto's on ethereum too. Ethereum doesn't limit anything they are ico or sto or just shitcoin. But being on ethereum chain doesn't give any confidence to users, you can make your own token in seconds very cheap. I think dusk network also trying to build this trust. Like this:
"Oh, it is on dusk network. That can't be bad or scam."
I am not sure how DUSK can limit someone from creating a token on its platform. How would anyone know beforehand that some token will be shit?
limiting anyone to create tokens would be a bad idea. it would turn off a lot of people.