I think the biggest issue is that number is harder to track. It's pretty simple to automate these kind of numbers and the number you're talking about requires s

I think the biggest issue is that number is harder to track. It's pretty simple to automate these kind of numbers and the number you're talking about requires self reporting by the project team and at least one, if not more Kickstarter employees to wrangle the data/facilitate the reporting. Though at this point they probably have enough staff to handle that.