Over Half of all online purchases in 2015 were on Amazon
For our ecommerce business we fought Amazon for years. Finally we decided to join them through the FBA (Fulfillment By Amazon) program – and our sales increased.
http://www.bidnessetc.com/59979-amazon-prime-subscriptions-to-hit-half-of-american-homes-by-2020/
Being an Amazon seller comes with the mistaken assumption that you can’t do much about SEO, as you’re working within Amazon’s constraints.