The thing I never understood:
The argument seems to be that "our payment partners don't like explicit content". I think the same excuse was thrown around for Tumblr's porn ban too.
* If this was a single (or small number of) player(s) objecting, why aren't they being competed around? Any payment platform that refuses to service the porn industry is, by its very nature, leaving money on the table.
* Again, if we're dealing with a centralized point of objection, I could see "name and shame" pushback being very effective. Imagine the backlash from both porn enthusiasts and libertarians closing their accounts if they said "It's XYZ Bank, they don't want you buying pornography."
* The worst-case scenario I could imagine is that it's at the card-brand level, driven by non-US/EU regulations. They can switch from (for example) Stripe to Braintree to Auth.net, but they can't escape Visa and Mastercard so easily. They might feel the need to regulate because it's required as a condition of market entry in, say, China or the Middle East.
But that still opens the door for domestic-focused alternatives (ACH? The old ATM-centric debit card networks?) In fact, in today's politically charged environment, I could see momentum to explicitly develop a payment product designed for "Western Sensibilites and Values" with an explicit "Hell no, it doesn't work in Beijing/Moscow/Baghdad" message. Suddenly, supporting pornography is a patriotic endeavour that you can use to demand special treatment and subsidy.
* Why now, when they're trying to go public? It's not like people suddenly woke up and said "OnlyFans had PORN?" If they maintained their relationships with their payment processors until now, it's not like there's a sudden, earth shattering revelation here.
I'm wondering if maybe the truth is less dramatic and grand. The angle I could see is that a hypothetical "OnlyFans - Porn" is a lower merchant risk profile than "OF as it stands". The high merchant fees for that industry are a well-established cost centre. If they could say "we slashed our merchant fees nn%" it looks good while preening the balance sheet for the IPO. However, I'm skeptical if that's the case-- any sort of "digital video delivery" and "subscription service" are still pretty high risk merchant types. I'd also think it's still less of a revenue risk to just split the business: a high-fee porn-only site and a cheaper-to-operate non-porn site, using shared technology.