>I think a lot of people will be caught by this rule because its so common in internet vernacular these days
"Common internet vernacular these days" is a large part of what Rule 8 is about, and "t." is less common than some of the other words and phrases that fall under the rule

It's also something you'll practically only ever see on 4chan/8chan/etc. on the English-speaking web (minus teh fags who adopt imageboard lingo on Twitter or wherever)