We call it pages, domains, servers, websites, internets and we hope the other party will understand. Maybe, maybe not, but that can always be cleared with the additional “wait, a server, don't you mean a website?” You can't just ask those questions when reading various specifications and technical documents, so they try to call things by their correct names and in a consistent manner. And they do it so well that terms like origin, site, same origin, same site, eTLD and public suffix are normally not even translated to other languages, because then nobody would understand it. And how does the attractiveness of subdomains relate to this?