Opening disputes (either with amazon or the credit card company) is basically the only way for funders to recoup any money from scam kickstarters. Saying they should accept it as an option would only mean more honest funders getting scammed out of their money if a project falls through should they go for e.g. bank transfer/cryptocurrency. No dishonest funder would willingly go for a payment method where their MO doesn't work. Enforcing it for high value investments means the honest investors have no way of getting their money back from a less than honest KS campaign.