What is the whole point of owning a business when you cannot have transactions with your customers? The payment gateway - a special processor responsible for moving funds from the customers' bank accounts into yours, is the main culprit. A hook up with this payment gateway is very important until of course your business is about providing products and services to the people, free of cost!
But not every payment gateway is compatible with every e-commerce platform. Technical limitations and lower demands for certain payment options are some of the problems which prevent a certain platform to work with the payment gateway. Depending on the countries you want your business to be established in, their payment gateways and payment options, you need to choose the right platform for the betterment of your business.