Some banks require an app for pretty much everything other than retrieving cash from an ATM, because they don't have a web app anymore:

1. Transfer money to another account. The alternative is to waste half a PTO to go to the actual bank (because they only open at working hours) to make that transfer.

2. Make an online payment. Most new cards no longer have a CVV (3 digit code) and instead require you to use the app to get a dynamic number. Many banks do not offer that option in their web app.

3. Forced 2fa for in-person payments with your card.

Today it's still possible to workaround many of these issues but they're closing these workarounds little by little.