In all corners of life, money overrides ideological concerns nearly every time. One or two zealots might join up to someplace like Patreon with fanatical goals of ridding it of smut, but in the end the people in charge will always accept legal money. The payment processors are the same way: for years, Visa, Mastercard, Paypal, and so on cheerfully processed payments to Pornhub, Xvideos, and many other openly pornographic websites.
What changed was the scope. Patreon got big enough to attract the attention of governments and moral activist groups who weren't thrilled about legally-iffy topics like incest, bestiality, and the like. Everybody loves money, but nobody loves law enforcement attention, major media articles, or Congressional subpoenas. The NY Times expose on Pornhub's shitty moderation allowing revenge porn to stay up (again at the behest of an anti-porn group) furthered this chill and caused the payment processors to think twice about working with adult content. Given the choice between taking a stance and having the larger business threatened, they'll always side with the business. It's also why Tumblr, Imgur, and (soon) Reddit are moving away from porn, because investors in their upcoming IPOs don't want any unwanted attention from anti-porn groups either.
TL;DR: You don't fuck with the money. If smut fucks with the money, smut loses.