If knowing an account exists is like getting to the moon, logging into it if it requires a private key is like getting to Andromeda.

I mean, I tend to turn root access off, but let's not oversell what kind of security it gets you. There is effectively zero security difference between a non-root account + passwordless sudo and a root account if they both require a key to log in.

I think jamiesonbecker was implying that this new user would have sudo restricted to just doing the tasks required for its individual purpose, not completely open sudo. I disagree with their point, but yeah, that would have nothing to do with guessing the account name.

no idea how to get notifications for responses to my comments, sorry.

No, I am mostly implying that the name alone is a risk. If you've ever brought up a box on the net, you know that the first account that's attacked is root. While the above moon/andromeda analogy is apt, some types of vulns could also leave you open as well with a known username to login with. Better to block those outright.

Plus, there's no reason to log in as root anyway as a simple matter of best practices; it's against virtually every security standard; no auditing of privileged access and hopefully no root account sharing!

heavy opinion: logging into a remote machine as root on modern Linux/UNIX is just laziness.