I read this topic when posted and rather blew it off. But thinking about it more, and particularly after @JoelR's most recent comment, writing the title after composing the post probably makes more sense. It it how we generally write anything more thoughtful. Yeah, we might have a working title, but, usually, we end up using something which is more informed by the body of the article/blog/book/etc.
What if the title field contained the placeholder text: Please first write your post
And, the poster is prevented from adding text to the Title field until content is added to the Body field. At this point, the Title placeholder text changes to:
Please write a title which strongly relates to the content of your post.
... and they can now add a title. In most cases, since the usual flow has been interrupted and they have been prompted to compose their post, the poster will finish writing their post before returning to add a title.
We could also move the Title filed to below the Body field. Though, might some people struggle to then find it since it is not in the usual location and many more would have forgotten about adding one? Though I suppose that when the title is missing, the webpage could scroll to place the Title field to just below the 'missing title' notice.