Page for posts – why?

What purpose does a ‘dummy page’ for the page-for-posts provide when using “static page” setting under the “Reading” admin page?

The dummy page concept appears to be broken and a source of confusion. Custom fields on the page-for-posts page are unavailable to themes, unlike on other static pages. (The same is true of the page’s content.)

Can anyone suggest a workaround that allows custom fields (and content), set in the page-for-posts page, to be accessed by themes?

Thanks.