I think your father probably said this, because many famous writers were alcoholics - Hemingway etc. I am the opposite with writing and drinking. I put a lot into what I write and focus a lot, so avoid alcohol. I don't drink wine anyway. Have a bottle of red wine for last 6 months unopened. It's not my go to drink. Makes me quite sick. So no, I don't agree that all writers are alcoholics, no more than other stereotypes about writers.