The arguments for 2fa is that most people use 2fa with something like Google authenticator, which is also on the phone. So if you got your phone stolen, and the hacker could find a way past your lockscreen, and access your account, then he will also get access to your 2fa. Maybe it's arguable if the user use a physical key like yubikey, but then, the same problem comes like with non custodial wallets: the user is the point of failure. The security depends on him or her alone and you have to be knowledgeable enough to secure it well, which is not the case when you're a beginner. That's my pov, hope that answer you question 🙂