There have been a number of failed/undelivered products on sites such as Kickstarter and Indiegogo but there have also been a number of successful projects. These sites leave due diligence to the customers. Unfortunately you are not alone in pointing out the number of projects that are not completed or completed with subpar materials.
What do you recommend the platforms do to help in situations where a project fails? I agree a zero responsibility TOS is an easy out but I am not sure there is a solution other than buyer beware. Almost all projects would fail if the platform would hold the money until fulfillment as they would have to borrow money to complete the orders. This would also add to the final cost as the business would have to factor in the interest, etc. One good thing that could come of that is that banks would see if the project had adequate funding to complete what was promised.
I am not trying to be difficult I truly just don't see a solution that works in these situations.