ok so the reason dio died is because he kicked with his left leg,the left side of his body which is, as he mentioned, weaker and slower to heal than right side, and also it was the same leg that got chopped off in half earlier by glass. not no mention his legs where already fucked by jotaro so the same would happen of he kicked with his right leg a stand is basically a manifestation of one's soul, meaning that of your stand explodes and dies or some shit, you die too,and no vampire healing bullshit can bring you back to life. you guys can stop crying about this now.