In some countries (Scandinavia...) not having the banking app is inconvenient, as it's used for authentication with many other services.
I would find it annoying if I had to carry the keyfob. I have it as a backup.
https://www.mitid.dk/en-gb/get-started-with-mitid/mitid-auth...
By using an app or various hardware keys — with a maximum of three active methods — they can reduce the chance that additional people have access, and prevent duplication of the private keys. This isn't possible with a QR code to scan for TOTP (you can scan it on multiple devices, or print it out, or have a computer with malware doing this).
Initial authentication is done using a passport, or in-person at a local government office for people without one (or without access to a phone capable of reading the passport's chip).
(This is just my general understanding of the system.)
Most apps I use (ie. banking) are bypassed simply by adding them to a hide-list.
The only apps that require a bit more work / expertise are apps that require integrity checks (ie. google wallet).
"A bit more work" but only for now... There is a loophole (spoofing the device fingerprint with the one of an old model where non-hardware attestation is still accepted) but Google is starting to ban those models and it's only a matter of time until they're all banned.