I think you missed the point. It's not about defining what experience people get, it's that as they are coming into your site, they get the right experience fo

I think you missed the point. It's not about defining what experience people get, it's that as they are coming into your site, they get the right experience for your content on their device, regardless of whether they were given a desktop link on a mobile device or visa versa. As demonstrated in the diagram, this is punishing people who strip the tails off incoming links so the link example.org/stories/good-news-everyone gets directed to m.example.org and the user is left with the mobile experience, but the wrong content.