If it's not then it's closed as soon as it's discovered though.

Why, is there some reason I can't just post vague messages which don't link me to any particular, identifiable human? How would they know?

I'm just saying that if they do find out you're not who you pretend to be then your account will be closed. A primary reason for this would be to prevent identity theft (e.g. accounts that appear to be a real person and add a group of people who all work together/study together/went to the same school).