Karen Horney doesn’t use narcissism as a category in itself. It's a nook in the vast terrain of self-alienation which she explores with startlingly crystalline insight.
She sees narcissism as a element which immobilizes and hampers self-awareness.
In her book Self-Analysis, she uses the word narcissism interestingly in a discussion of Freud’s attitude towards the nature of the desire for self-improvement. Freud dismisses this desire as a "narcissistic" tendency towards self-inflation and excelling others:
"What Freud refused to recognized is the fact that this 'narcissistic' element is a contributing factor only. If the need for self-aggrandizement has been analyzed and abandoned, the wish to develop still remains, yes it emerges more clearly and powerfully than before. The "narcissistic" elements, while they have kindled the wish to grow, have at the same time hampered its realization. To use the words of a patient: "The 'narcissistic' impulse is towards the development of a phony self." The fostering of this phony self is always at the expense of the real self, the latter being treated with disdain, at best like a poor relation."
(When not quoting she doesn't use the term "real self", but tends towards pointing out the difference between possible and impossible self, and static vs. dynamic self etc.)
So narcissism is seen as a paralyzing feedback loop in the circuit of the character structure. It’s a drag because it prevents new information from entering the system.
It’s not hard to think of examples of writers who essentially use poetry to create a fantasy image of themselves which they are trying to get the reader to validate, even if this is done indirectly. I see this across traditions and styles. Work of this kind is tiring to read. You feel used. To what extent is poetry used as a place where one is allowed to more safely harbor and nurture one's neuroses?