There are two aspects to friction as it applies to a website or any product. One, you make it easy for the customer to do what she wants to on your site. Two, you make it easy for the customer to do what you want her to do.
In the e-commerce context the second aspect manifests in a way to make it easy for customers to leave a product rating/review. Not only does this help future customers make their decisions but also helps the site collect all important explicit rating data to build a working recommendation and personalization system. Without explicit rating data it becomes impossible to implement a user-item collaborative filtering algorithm to drive recommendations. So it is in the best interests of the site to make this as frictionless as possible.
This is Flipkart’s user profile page. It just tells me that I have not rated or reviewed any product. But it doesn’t make it easy for me to do it.
Had I not made any purchases this would have been fine. But as you can see that is not the case here.
And even when I clickthrough, the products bought are not hyperlinks to go and give ratings. Option? Copy the title, paste in the search box, hit enter, look up the product in the search results, clickthrough to the product and then give your rating/review. Not easy. Too much friction.
If the products bought were instead listed on the profile page with shortcuts to rating stars and a review box the friction would have been lesser. Then the focus could have shifted to how actually to get customers to provide this feedback.
Images from my account on Flipkart.com.