The sad part is it's hilariously easy to do both, and the platforms take about 5% on top of the transaction fees the payment processor takes which is a wash of 3-4%. That might not sound like a lot, but it adds up to thousands on big campaigns and the platform keeps all of the info of the supporters as far as I know so it's harder to reach out to them for future campaigns and products unlike with a website where they can have direct communication with supporters.
Payment processing is also usually a plug and play solution from either one of the big processors or a bank directly, so it's highly unlikely it goes down unless you screw something up or get hit with a velocity attack because you didn't have basic safe guards.
Edit: Oh, wait, it can be way worse than 5% at IGG's discretion, lol, lmao even.
And