GNOME does not serve anybody: we are aiming at making a desktop for everyone, but it’s a volunteer effort, and y’all aren’t really paying for a product.
Making a desktop for everybody entails, by definition, the ability to reach out to people that are moving away from existing environments, none of which have a primary selection buffer separate from the usual clipboard; most of them have uses for a middle click gesture, though, and it does not involve pasting text.