What is the reason for using the page's header as a link to itself?

Question

I noticed many web sites use

<h1><a href="/subdir/somepage/">bla bla</a></h1>

in the page example.com/subdir/somepage/

Why do they do that? SEO? Compliance to some standard I don't know? Does it really help users in any way?

EDIT: after many of the answers obviously misunderstood me. I'm not talking about a link to the homepage of the site. I'm talking about a question page in SO using the question's text in H2 element (see that above?) to link to the same page.

Answer 1

if I want to cut and paste a page link, it's one operation (in Firefox) to right-click the page title and select "Copy Link Location." Swiping (or doing select-all) on the URL and then hitting control-C is two operations.