> "Well that's not really true. There's most definitely functionality that is only available in the app. If I want to make a payment without having to dig a card reader out every single time, I absolutely have to use my bank's app."

Maybe not for you, but you don't know his bank. Obviously I can't pay with my phone if I sit at my computer and use online banking in browser, so obviously payment with phone app won't work if I use browser on phone, for all other online banking functionality there is no benefit in the app, all of my 3 banks I regularly use don't require any card reader or even smartphone, all I need is any phone being able to receive SMS with 2FA codes, if my bank required app to use online banking I would just stop using their services. I am not going to bother with app in the phone while sitting at computer with 32" display and proper keyboard.