This article is a bit unfortunate as it complete segments the issue. I am not asking for calculation of minimum relative urls like they referenced, (eg: ../contact) or similar. I’m just saying leave out the domain.
Let me rephrase: absolute paths are fine. Absolute URls have no benefit.
WordPress can do canonical 301 redirects without throwing the domain on every single resource in a page.
I have a site with about 80 occurrences of “http://domain.tld” on every page.