Is poetry writing therapeutic?

Forms of poetry

Most people who read poetry have heard of Sylvia Plath.She was only 30 when she died but  is now a top poet of the 20th century… her  ambition was fulfilled.But if poetry writing is therapeutic as many people believe,why did it not help her?
I read an article about this  but am sad to  say i can’t find the reference.The author claimed that writing  structured poetry like sonnets is more likely to be therapeutic.Nowadays though,free verse and non structured  poetry is what is fashionable.Rhymes are not.Think of modern music cocmpared to Schubert or Haydn… you get the point.
Plath’s poetry was ,in a way,violent.She went to her depths but as she already had suffered a severe breakdown and  more recently  was deserted by her husband her depths were full of pain and anguish.And she had sole care of two little infants.Was it worth it?
So it you feel you want to write for therapy,try writing in  a traditional form.The structure contains the feelings better.