Very, very simple: Me and you are humans using a machine. So looking at this example you posted:
ssh-rsa [piles of gobbledygook]…CA9gyE8HRhNMG6ZDwyhPBbDfX root@mydomain
A machine can read this:
ssh-rsa [piles of gobbledygook]…CA9gyE8HRhNMG6ZDwyhPBbDfX
A human can read this comment:
People tend to forget that even though things might look complicated on computer systems, they could actually be tons more complicated if the code was designed only for machine consumption. I mean look at obscured malware code. Once you decode it and format it, it’s human readable. But someone had to go out of their way to make it hard for humans to read.
By default all types of coding and configuration files on a computer system are structure for human consumption because… We are humans using machines and machines don’t need things like:
- Variables and functions written in a human readable language.
So the comment is meant for you and me and nobody else. It would most likely work without a comment. But that one time something is not working at 3:00am and you are hunting for the right public key, you’re going to wish/dream/pray the comment is there.