Banks frequently refuse to do business with, or heavily restrict, businesses that they deem risky from a financial perspective. Adult content, pharmaceuticals and travel are all industries that experience significantly higher occurrence of fraud and chargebacks than others. For example, your spouse sees a weird item on your credit card for a porn site. "Wasn't me! Must be stolen I'll report it." Sometimes it's the other direction. Travel businesses often get by on very thin margins with any significant balances due to deposits. If something happens, customers might get deposits back, or they might get chargebacks, and the business can rapidly end up deep in the red.

Often times to bank successfully you need large stagnant balances that are semi-frozen, or meaningful collateral.

This becomes problematic through payment provider platforms which other platforms build upon: it's not straightforward to manage these relationships through so many layers of abstractions. It's easier just to ban the industry.

I don't know the specifics of Kickstarter, but I've seen this happen countless times, so it's not difficult to connect the dots.