These issues make it clear that having an ad for “Install App” has a high cost in terms of causing an often severe negative impact on users’ product-browsing and -purchasing experience on the mobile website. During our testing “Install App” banners were the direct and sole cause of several abandonments of some of the world’s largest e-commerce websites.Mobile E-Commerce UX: Deemphasize ‘Install App’ Ads or Avoid Them Entirely

Even for e-commerce sites that I visit on a weekly basis, like Mr Porter, I would never install their app.