Yes there is. There are more than one, in fact. People who make accounts through Steemit to get the delegated SP, so they can vote, provide a phone number, and those that do this to create botnets use fake, temporary numbers.
2FA ends both creating accounts this way, and having more bots than you have phones.
Anothe mechanism, which I personally detest, is captchas, at least a temporary fix, until AI gets smart enough to beat them.
You're smarter than me, and can prolly come up with even more.