Say your are an advertiser with an ad click or have a visitor come organically from social. They like your products and place them in their cart and go to checkout, at checkout they want to use Apple Pay or their saved card details. These aren’t available in most IABs, so they click the “open in browser” button, but now they have lost their cookie and have an empty cart! This causes a massive drop out rate at checkout.
I run a store that sells personalised items, it takes time for a customer to prepare their item before going to checkout. We experienced something like a 30% drop out rate from Facebook ads due to this.
The “work around” was to detect users in an IAB and display a message on first navigation attempt to prompt them to click the “open in browser” button early.
The fact that Facebook let this happen shows that have very little interest I’m making the advertising experience better for advertisers. They just want to keep users in Facebook.