Why are my teammates always terrible?

Look I'm not the best player on the planet but if My teammate, a rampart, has her mini has done severe damage to an enemy, I pushed the building that enemy has gone into because it's the right thing to do to gain a knock, to turn a 3v3 into a 3v2, unfortunately that rampart didn't come with me even after seeing me use my ultimate, I'm Maggie, so I've done substantial damage to all 3, knocking one of them and doing substantial damage to the others. Meanwhile, my other teammate The mirage he's off in another District looting, then I naturally get pushed 2v1, The rampart unfortunately decides to back off meaning I'm screwed, then she dies and complains at me 

Why are my teammates always substantially worse than me, And my enemies always substantially better leagues above me