As a game developer who sells virtual goods, I don't care how hard it is to implement my payment solution. I care how easy it is for my users to use and how many will use it. Stripe claims they are easier to implement. I don't care. They have to show more people will buy if I use Stripe instead of PayPal and that just isn't true. PayPal has far more people who already have accounts and who just have to type in a pin or password to pay. Compared to typing in a whole card, the increased number of users who will buy is really big. Make your users have to do anything difficult and they just won't most of the time. That's the facts of life on mobile. They especially don't like to type.