That sounds fantastic for more technically sophisticated users… but I strongly suspect the reason banks continue to use phone, email, and SMS is that most users

That sounds fantastic for more technically sophisticated users… but I strongly suspect the reason banks continue to use phone, email, and SMS is that most users aren’t that technically sophisticated, and strongly want to use the (admittedly unsuited) communication methods they’re already familiar with. There was a post here a while ago about the debt collection industry that had a section of which the essence was “You’d be shocked at how little many people understand about banking and technology and basic math”.