Pretty sure most of you already know this but for those who don't: you have two clipboards in Linux. One is the traditional clipboard where you copy with control c and paste with control v. The other one is when you highlight text and use the mouse middle click to paste text.
More details here.
I don't get it, why would you even be mad about someone referring it as GNU/Linux?
In that case it's even just either X org or the wayland compositor that may implement that, not "linux".