If you disclose your school and a few other tidbits, it would be pretty easy for anyone at your school to figure out who you are. Also, as to others who don't go to your school, many people on the internet will browse through your past posts to find something personal to insult. If rank is somehow relevant to the conversation, disclosing a range is usually sufficiently specific.
I find it much more obnoxious when people disclose the rank of their school in contexts where it is irrelevant. "I go to a T14 school, and I was parking my car the other day when I spilled my coffee.." Give me a break, if you are that desperate to gloat you are obviously a very insecure person.