What am I?
Frequently I appear,
Not just here,
Applesauce I make,
Did that hold you up?
Vulnerable I am,
Annoying I can be,
But required I am,
To hide what could ruin,
A soul's own zeal,
For what is frequently here.
You are
The rot13 substitution cipher
Frequently I appear
It is used frequently to hide spoiler comments
Applesauce I make
Applesauce as a term can mean nonsense, which is how rot13 text reads
Vulnerable I am
It's an easily breakable cipher
Annoying I can, But required I am, To hide what could ruin
The cipher is used to hide comments which would otherwise spoil puzzles
Additionally
The title is a rot13 of "I stare you in the face"