It can also be your writing style and how effectively you communicate. I'll need to check your latest post (didn't have time yet).
I don't buy that for a second. My writing skills are at least comparable with the posts that make it to the front page daily. I have made 4.0s in all of the English classes I have taken.
It is the topics I am writing about, and the fact Steemit is a popularity contest. I have never been good at the latter.