I tend to not believe that we did a whole hell of a lot solo. After all, one of the big themes of the game is "strength through unity," so for us to slay Primals and the like on our own goes completely against that. Plus, there are more than a few times that NPCs will outright tell us to gather up some friends before we take on threat-X, Y, or Z (Void Ark and Alexander series comes to mind), and as infrequent and inconsistant as that is, it still makes more sense that we teamed up to take on most major threats.