Yes.
It is only right and proper that the, 'you need to learn the rules, before you can break the rules' axiom is trooped out to sit upon the fence at any discussion upon grammar variations or deviations within creative writing. No conversation upon the subject would be complete without it and we are well to be reminded.
However, the discussion here is more to do with the fact that correct grammar can often make prose within creative writing stiff and less eloquent.
I mean, in order to make creative writing a better reading experience the ‘advised best practice’ is against grammar in several respects. For example, ending sentences with prepositions isn't actually incorrect in grammar but it makes for inelegant writing. Similarly, Split Infinitives, Passive Voice, starting sentences with ‘And, or ‘But’ are actually perfectly acceptable within grammar. No law against them, but you wouldn’t want to write like that because it makes the writing appear unstylish and unprofessional.
What we are talking about here is why do we (or the majority of us) write ‘Who’ when the ‘who’ object is a preposition or an objective case and grammar law dictates we should actually be writing ‘Whom’
As with the eternal, ‘hanged’ VS ‘hung’ debate, so ‘the couple are sat upon the sofa’ VS ‘the couple is sat upon the sofa’.
Should we write the way we actually speak, or must we write the way we don’t speak?
Does grammar define the language or does language (eventually) define grammar (proven by international differences within 'English' Grammar definitions) ?
Writing dialog is simple. Niles Crane speaks the same language very differently than Rocky Balboa. We can depict this. Narration is dialog too; the writers voice. Would I write (and expect to read) a different writing style within a romance novella than within an essay, an inventory or an affidavit?