I thought that Kickstarter/Indiegogo had effectively become this. A common complaint is, "hey, I launched a Kickstarter, got funded, and some Chinese factory stole the idea!"

My response is always, "so? Aren't those sites more for 'I wish this existed so I could be a customer' than 'I want to personally profit from this idea'?"

So, yeah, if you don't care about someone stealing it, you might be able to repurpose Kickstarter that way:

1) Start a KS for the idea.

2) Wait for someone to steal it.

3) Cancel and refund everyone's money.