A random app cannot eat your passkey. Platform authentication ensures more safety. I am not an expert but definitely it does use secure enclave in some ways(maybe decryption).

UX usability is far better. With password and 2FA you have at least 2 steps. Here

Open the app: device like phone or laptop just asks your fingerprint or facial and done.

That is a great benefit for average Joe. Some one trying to scam remotely cannot access the account. The 89 year old grandma will say - I just give fingerprint. Done.

Yes, it won't cover all situations. Like if there is sim swap or bank employee does fraud.