Are you a programmer? Computers suck, internet sucks, electricity sucks, all engineering devices fails, things rot, there are bugs, unknown unknowns, unpredictable situations, the UX is poor, the code is old and no one understands it, people have different requirements and no software can ever be as flexible, spaghetti is real.
My bank apps fail at completely random times because of React Native or because of unknown server errors. Credit card machines fail or just lack connectivity at random times. I have to keep 3 different bank accounts because if I really need them for something I am always at risk of one of them just not working -- not to mention the fact that they sometimes just decide to ask me to take a picture of my face or something like that because of their own reasons.
And you want us to all move into a single central system completely closed, run by bureaucrats.