How is it "literally the only way to counter scamming sellers"? There are so many competitors out there that offer better services... Stripe, Google Pay, Moneris, Braintree, Square, WePay, Authorize.net, the list goes on...
Edit: also googling around none of those seem to have the solid buyer protection that PayPal has. With PayPal I can just open a dispute with a picture of the error (color is off or whatever) and within a relatively short time period the seller is forced to reimburse me the full purchase cost, including shipping. That's very valuable as a customer.