Creators have obligations. This is true whether they are legally enforceable or not.
Morally the backers also have obligations: they should research the initiators, but almost nobody ever does. They should reflect on the feasibility of the proposal, but instead the 'it would be great to have this' feeling combined with 'wow, that's cheap, they can't possibly make it for that kind of money so let's back this' is a near certain path to disappointment.
Kickstarter is the main party that has obligations but they disavow all of these and obviously they have the legal backing to ensure they are not on the hook for any of this. On top of that they keep backers structurally in the dark about the risks.
Edit: a short afterword: I've had many, many requests to do a Kickstarter for the Lego sorting machine. I could have raised millions of $ with ease for this project. And I didn't do it. The reasons why are because I know the difference between making a prototype and making something aimed at the general public, I realized that people's expectations of delivery are unrealistically high because there are a lot of unknowns in a project like that and finally that I would not want to risk my reputation and existing business on a project like that. But not all Kickstarter initiators have that much experience in industry and even if they self evaluate to 'I can do this' it may simply not be true in practice. This is the bulk of the Kickstarters that fail on the delivery. To then demand the money back would put these people in a hole that they won't recover from for the rest of their lives. So the default should be: project fails, backers lose their $ because the same thing that allows Kickstarters to succeed is what would put the initiators of failed projects in the poorhouse: it's $50 for you but $50,000 for the initiator (or more) and once that money is sunk it is not recoverable.