I have use many marketplace website and all of them are using their own Money balance system. I have to add money to my account with PayPal and then I can buy services from their website. Why is that so? Why cannot I pay directly with PayPal for each service? Are they afraid of chargebacks?
They make a commision each time your add money on account, thatswhy they use these payment processors.
They can make commission with direct PayPal also. Buyer send money to website owner PayPal account, they take the commission and send money to the service provider. Fiverr.com is not using balance system.
Could be for several reasons. Charge backs would be a major concern. Another one is that people often hesitate making the purchase as soon as they wonder if there is enough money in their bank account. Eliminating this fear and enabling a single click checkout can create an environment, theoretically, where the buyers can buy faster and have to reload again. Another concept in doing this is one of a reserve. It cuts down on the tire kickers. Put down money - show you're serious.
Sometimes its simply easier for you as a customer. You go to the website to check something out, you notice you still have some debit with them, click -> buy thingie without getting your credit card out or login to a transfer service (like paypal)