My understanding was that they were being cut off by payment processors and banks and that drove the decision. Was this resolved?
I would also like to know on whether it's possible for someone to start their own payment processors? There are tutorials on how to start an ISP, so should be possible for payment processors too no?
There's a few players here:
payment gateways, this is a service that provides the checkout service on a website and handles protected credit card information. Payment gateways also provide anti-fraud services.
payment processors, these execute the actual transaction. They are members of card associations like Visa and connect the card issuing bank and the merchant bank of the payee.
merchant banks, these are the banks that hold the company's bank account that the funds from the payment processor come into.
card associations, Visa/Mastercard these provide the connectivity and set the high level rules.
card issuers, these entities extend credit and may be retail banks or other parties.
there is a difference between Amex/Discover and Visa/Mastercard in that the former are also the issuer. That's why you also see Visa debit cards in Europe, they're using the payment processing network but not extending credit.
It should be clear that starting a new payment gateway is trivial. It takes money to properly comply but ultimately this is a software business. Starting a new payment processor is much harder but it doesn't matter because all payment processors must comply with the card association rules to get access to that network.
Starting your own card network would require attracting issuers who would then issue cards that people could use to pay for OnlyFans... probably not realistic!
It was the threat by Visa and MC to cut them off that was the killer here, plenty of payment processors would be happy to take their money but not if the card networks ban the company.