I don't like the edit at the bottom where the author's like: oh yea, of course this could be a massive issue against FOSS but we should just assume that vendors will think it's impractical. I've seen how banks react to rooted phones, even when rooted to heighten device security--and I've switched banks before because of it. They don't care.
The banks not much better. All banks in my country have dated late 90s-looking websites with not even UTF-8 encoding (so you can't send an email with a comma). They are barely usable on desktop. I'd have to make my own client or at least whip up a lot of magic CSS to get it to be mobile-friendly and would even still need to include QR code scanning as it is so ubiquitous that no one would let me fiddle with adding their account numbers.