No, passwords on their own are never "enough" for you to be secure as you only control your side of the equation. You don't know if the place you are storing it is doing so in plain text, storing a decryption key right next to it, etc. Even if you are careful (I know what you said above), the network you are on could be compromised despite your best efforts/knowledge. Or any number of other things that could make it trivial for someone to gain access to your account in the event they gain access to simply the password.
I don't claim 2FA is perfect, it has its own host of issues as is being discussed. But it isn't just for "the masses that don't understand how to make strong passwords or how to be secure". Certs are good, but they need to be made simpler than they are now for the very people you claim 2FA is for or they won't be adopted (one of the reasons they aren't more ubiquitous, IMO). And some certs implementations have issues with account recovery as well if you lose access to them.
It's a really hard problem that you do a bit of disservice to when you dismiss it as "just a problem of the plebes".