On stream pages (tag, category and search), the data describes, the owner of the blog and lists all the items on the page. The structure is just a simple list, as the crawler can get all the information from the structured data on the permalink pages.
On the blog main page, the data only describes the blog as an organisation entity. We can’t list the items here, as there is no guarantee the post in the list was authored by the current blog.
There are case studies showing that including well formatted structured data on the site can lead to increases in traffic, so we are looking into how to improve our structured data even more, especially on permalink pages.