Meh, it's common to want to navigate to the root of a domain to find more information if you've been linked to a subpage that may lack some useful context. You can of course edit the URL by hand, but that's less convenient. Intra-site navigation links have a purpose.
(Perhaps on another timeline browsers would have had an "up" button in addition to "back" and "forward" like filesystem browsers do, but that did not happen. Even <link rel> doesn't have an "up" option, though it does have "prev" and "next" – not that anyone uses <link> for anything but rel="stylesheet" and maybe rel="alternate". EDIT – rel="up" used to exist but was dropped from HTML5 with no reason given. I presume it's nevertheless supported by browsers and eg. screenreaders.)
(Perhaps on another timeline browsers would have had an "up" button in addition to "back" and "forward" like filesystem browsers do, but that did not happen. Even <link rel> doesn't have an "up" option, though it does have "prev" and "next" – not that anyone uses <link> for anything but rel="stylesheet" and maybe rel="alternate". EDIT – rel="up" used to exist but was dropped from HTML5 with no reason given. I presume it's nevertheless supported by browsers and eg. screenreaders.)