so many email servers?

what's the point in having so many email servers? i use gmail and sbc global, but i think gmail is the best email because you can chat with people. i don't know if hotmail can, but yahoo has instant messenger. gmail gives you some good stuff like, igoogle, this blog, and other things. the good thing about yahoo is that you get to do yahoo answers. i'm just wondering, but what kind of email do you use?