Note that HN is abiding by common customs that many people on the internet will have encountered a lot: usernames are clickable, things in the header/footer are

Note that HN is abiding by common customs that many people on the internet will have encountered a lot: usernames are clickable, things in the header/footer are clickable, "action words" without context are often links (i.e. "link", "parent", "flag", "comments").