Why quit and why go alone?!

Why do so many people quit after they die, and why so many people in duos just run off on their own? Like why are you playing duos if your gonna quit when you die, like how about have some faith in your duo, maybe give them a chance to revive you? Or ya know...Just play solo! Ive had so many duo matches where they leave after they die, thet dont even give me chance to grab their card. My thought about people who leave are "wow someone thinks highly of themselves", "wow fun another fuckin loser yaaay". Its borderline pathetic when they leave xD