Why do people split into Team Edward or Team Jacob?

Hello blog readers! I'm very confused about something, why must there be two seperate teams? Team Edward or Team Jacob. I hear it all of the time. Though I have given in, and stated my love for Edward on the Team Edward side, I have still been annoyed countless times hearing arguments back and forth. Is it only based on whom the reader thinks is cuter? Because honestly, and if you haven't read the last book yet, don't read this next part, they all come together in the end to protect and save something they both love, Bella! So who is the rocket scientist who decided that they were automatically permanant enemies. To the people who actually LIKE the "team" idea, sorry if I have offended you. Actually, to tell the truth, I'd like to be on team Alice!
Okay I think I have stated my point. Farewell. TEEHEE!