This is the product PayPal advertises in every single purchase customers make online. I don't understand why any serious business uses PayPal for payments when the company is injecting an extra step (or two) into the purchase workflow. How many sales do merchants lose because of the interruption?
Despite the fact that the PayPal button is tiny compared to the credit card form, a full 2/3 of customers use PayPal to complete the purchase.
That's why people use PayPal, because a large percentage of customers prefer it over credit card payments.
Also, I prefer PayPal disputes because they don't charge a chargeback fee like credit cards.