This is not true. SSH keys are a viable alternative.
Carry your phone (many people already do this on a daily or near-daily basis in 2024) and use that in an emergency.
If I can be charitable ....
What the hell are you doing storing your SSH keys on-disk anyway ? :)
Put your keys on a Yubikey, take your keys with you.
I'm not arguing it isn't more secure. The point of this subthread is that SSH keys are not as easy to do ad-hoc as passwords, especially when moving workstations.
Extremely easy to recover from when the device you rely on to authenticate for everything gets lost or stolen too!
If I can't use TOTP with backup codes, I'm not using MFA.
ssh-keygen -t ed25519-sk
If I recall correctly, the SSH binaries provided by Apple don't have built-in support for signing keys, but if you install OpenSSH from Nix, MacPorts, etc., then you don't have to worry about this.
Another thing to be mindful of is that some programs have a very low timeout for waiting on SSH authentication, particularly git. SSH itself will wait quite a long time for user presence when using a signing key, whereas Git requires me to confirm presence within about 5 seconds or else operations fail with a timeout.