What is wrong with 4 man premades?

Ive played with three 4 man premades tonight and many more since starting, and they almost all act the same. It's like they are not only completely ignoring you, but trying to make a game out of baiting you in to fights or watching you die from 3 steps away. I wouldn't care if it was like any other game where someone occasionally doesn't notice or isn't fast enough to react, but i'm sick of 4 man premades going out of their way to completely ignore the fact that they have a 5th member on the team. Oh, except to blame them for everything at the end and 4x report.