EDIT: apparently the OP meant SMS password reset without requiring the second factor, not SMS 2FA. Of course that's terrible.
If I want to compromise your account, I force fallback and then compromise your SMS. Security is as strong as the weakest link.
It's more like you have a deadbolt and a regular lock. Sure, you can open the regular lock with just a credit card, but that doesn't help you with the deadbolt...