it's not the browser itself, it's the experience of staying in app when clicking a link. for example when going through a paygate that redirects to a browser. i don't want to leave the app, then come back in manually. with an in app browser it works seamlessly.
What does "in app" do differently? On Android the only thing I can think of that is different is that if I open the app switcher the tab is in a different app.
But I think I prefer that because if I click around a bit I can switch back to the app that spawned the tab directly instead if hitting back a load of times.
when in-app and i close the browser i'm back in the app. this isn't the case if i'm redirected to a different browser application. That's quite a big deal