I read an article a while back suggesting that among their other problems, in terms of honesty and ethics, self-help books are always dreadfully written.
My reply was that in a way you could call Kahlil Gibran's The Prophet an OG self-help book, which nonetheless fulfils literary standards.
I've been mulling the idea over for a while and have started writing a book in a similar vein - episodic and allegorical life lessons presented in a narrative structure as the teachings and experiences of a guru figure.
If I ever get it finished, I'm not sure what category I would publish it under.