Agreed, and I think a larger part of it is that most folks pick it up based on context after long enough, so it's rarely explained. The square brackets are optional arguments. So I could use ssh 192.168.1.1 or ssh postimo@192.168.1.1 with the first asking for the account after I connect, and the second just asking for the password. You can see how the computer took it in the response you got. hostname ]192.168.1.1 being it saw the @ and assumed everything after was the hostname and included the ]

It's worth noting that you can't just connect to a random machine like this, they need to also be running an ssh server. But I wouldn't expect you to know that without reading a great deal more of the documentation 🫠