A few years back, there was a major upheaval with PayPal. Those of you affected surely remember it.
Sensual and erotic publishers and authors had their accounts frozen by PayPal while they "investigated" claims that the members violated terms of their very-amorphous adult content rules. They even froze publisher pay accounts, which had nothing to do with the actual sale of books that might have broken the policies. The money was held for indeterminate periods of time and without the ability of publishers and authors to adequately communicate with PayPal about the situation. Notably, some of the higher grossing erotic publishers were immune from this process, and smaller publishers and authors, even those who had checked their content past PayPal before the policies were finalized and who had been assured their sites were fine, were ravaged by this abuse of PayPal's powers.
So, why then are we still using PayPal? Why are we still clammoring for publishers to take it?
Simply put, the readers ask for it, and the publishers comply. PayStone, as wonderful as I find it, isn't yet available worldwide, as PayPal is. Merchant systems rarely take all of the credit and debit card types people want to use. The most complete system we have at this time is PayPal, no matter that publishers and authors have to watch our backs with them, because they seemingly don't know how to apply the Supreme Court ruling on what is obscene to their business dealings.