Because long post make your post looks high quality, this will give some advantages like:

1. The moderator will high unlikely to delete your post.
2. The campaign manager will count the post without going to check the point/message of the post.
3. Merit sharing with alts will be hard to busted because people think long post deserved to be merited and merit is subjective.

I'm not sure if it's healthy or unhealthy for the forum since no one has a right to change someone else posting habit and as I said above, the moderator won't delete such post. So it's what it's.