I've not seen it defined as such, but the novelty of the hashtag isn't quite as novel as one may expect. Hashtags were meant to help people search and find conversations a concept that is generally the direct negative of the preceding generations' version of leet speak (or l337 speak), which was commonly used online as a means of specifically preventing simple search as specific words were replaced with coded equivalents. As a coder and technologist who grew up in the age of leet, Messina would have certainly been exposed to this culture and way of thinking.