Beckett does it. Shakespeare does it. Orton does it. Moliere does it. Seneca does it.
Genet does it.
Mamet does it. Churchill does it. The writer is there to give body to our desires and fears, to give them voices and to shape their destinies. The writer will use everything he or she has, all the skills gained painfully over years of experience, all the knowledge pillaged from those who have written for the theatre over hundreds of years, all the poetry they have within their being, all their imagination, all their grief and anger, all their joy and all their love. There are no rules.