AFAIK, Indiegogo has a $500 minimum. Not for keeping the funds, just as a minimum goal.
It is an interesting strategy. But I think the advantage isn't the obvious one of 'keep everything you raise.'
One of the things that hurts campaigns on KS is that random strangers browsing the site only see like 1% of the projects.
Setting a $1 goal could get you on the page as a 'successful' project which means more people browsing for projects to fund will see it. Now, it will be obvious to the person browsing that you're only 'successful' because you set a $1 goal. However, it will still get in front of their face and they may watch/read your pitch and choose to donate.