Higher elo please explain

Why I was the one they wanted to blow all their ults on and then my team clean them up? I mean, I am a tank. I deal like almost no damage. I don't understand their obsession with wanting to go straight for me. You could have stuck Caitlyn side by side with me and they would still go for me. Is there a reason you can surmise that they wanted to go for me? Cause let's be real I sucked it up bad that game.