"is for creating one introductory post that tells us about you"

No it isn't. There are no fiat rules in regards to how often the introduceyourself tag can be used. There is nothing in the white paper or terms and conditions that specify you can only post in that category once. If a post is relevant to the category being tagged then it is obviously appropriate. This is a post that expands on the previous one regarding what BitF is all about and is completely related to the category.