The “introduceyourself” tag is for creating a post that tells us about you. Users are encouraged to use this tag exclusively for that, and not to reuse it.

This was the reason why I used the tag, since this is a post introducing my personal background relevant for my Steemit posts, to allow people (especially new followers) to get to know more about myself. I have seen other well established users writing "re-introductions" after they have acquired a significantly bigger number of new followers, so I thought it was allowed to do something like that (this is only the second time I use this tag). However, if it is strictly not allowed to use it more than once, then I certainly won't do it again.

Thanks for the heads up!