The reason is: larger businesses will require more payment options than Stripe offers.
India? Adyen got you covered: [1] Philippines? Yup, everything [2], including offline payments in stores [3]. Mobile payments in Africa? No worries [4] And so on and so forth. On their payment site they don't even list all payment methods, there are so many. You search for a country or a payment method, and they show what's available.
Stripe has a very long way to go to realistically compete with Adyen.
[1] https://www.adyen.com/payment-methods#pmx=india
[2] https://www.adyen.com/payment-methods#pmx=the-philippines
[3] https://www.adyen.com/payment-methods#pmx=convenience-stores...
[4] https://www.adyen.com/payment-methods#pmx=mobile-network-ope...