Problem is that the category of users who can be tricked over the phone to tell someone OTP are people who just won't be bothered to use external devices like y

Problem is that the category of users who can be tricked over the phone to tell someone OTP are people who just won't be bothered to use external devices like yubikeys - they're a hassle, you need to carry it around, can loose it, costs money, etc. 2FA is a middle ground, it's free, it's already with you as you carry the phone anyway. Most of ordinary people can be talked into actually using it, and while not perfect it provides a lot more security than just passwords... Security always goes against user's convenience, just like the privacy... and in real life, as a rule of thumb people tend to almost always choose convenience, first of anything else...