As far as I know, the drafts feature isn’t meant to be similar to email drafts. This is more of an auto save feature if the website or Discourse App or Browser crashes or if you accidentally close the tab while creating a post.
Vanilla Discourse doesn’t have a way to save drafts directly, for mobile you have to forcefully close the app/browser/tab after the draft saves and for desktop, I think you just have to press the escape key.
This seems like a feature for overall Discourse, so this has to be suggested on Meta since our community won’t directly benefit from this.
might create another how to guide for posting forum features