I can't speak for GP but we have mobile-only* banks in my country too. They usually have better interest rates, let you easily pay your bills from the app and let anyone open an account with just an ID. Many traditional banks have a lot of not so easy to meet requirements for opening an account and not so good customer service. Old people still use traditional banks because they are used to them and don't mind waiting 4 or 5 hours in queue for something that only takes 2 minutes on an app or a website.

* To clarify this, I don't mean banks that require a mobile app for TOTP or some sort of security, I mean banks that only let you operate through their mobile app. Their website is usually just a link to the app stores. and some FAQ, they don't have a physical location you can go.