There's a lot of confusion about some tags. A lot of people reasoned the same as you and kept using it for everything about themselves. It's use is actually interesting as it changed over time. When Steemit first launched many users didn't start off with an introduction post and instead would post one after they already got a following. Now, its encouraged to make the initial post an introduction. Because the initial post is so important the use of the tag is heavily moderated.