The PnP D&D5 games I play certainly don't link XP to killing and looting.
My current GM, in fact, doesn't even bother with XP but simply levels us when he feels it appropriate. It works. I can't remember the last game of Pathfinder or D&D I played where we gathered XP simply for killing things, it has been linked to story and completing quest-lines for as long back as I can remember. That's the beauty of PnP RPGs, your GM/group can determine how such things are handled.
