The designers fixed the problem simply. They took away the Register button. In its place, they put a Continue button with a simple message: “You do not need to create an account to make purchases on our site. Simply click Continue to proceed to checkout. To make your future purchases even faster, you can create an account during checkout.”
The results: The number of customers purchasing went up by 45%. The extra purchases resulted in an extra $15 million the first month. For the first year, the site saw an additional $300,000,000.
This is my favourite story to tell when talking about why a registration/login flow is a huge obstacle for users and why you should have an alternative for it.